manual disc brakes?

Only car I drove with manual discs was a Shelby GT350H Mustang, back in the day, and the sign on the dash wasn't enough - "takes more effort" was an understatement!!
Took BOTH FEET to bring it down from over a buck, at O'Hare - Old Manheim Road, before the curve!!
Took the curve at about 70!!
A car that took a pole into the back seat, that Hertz paid to fix!

On my 67 I converted the front drums to manual disk when I rebuilt the front end. I lost the vacuum needed to continue using the power assist with the cam set up in the 455 build. I think the car stops fine. If I didn't think so I would have looked into adding a vacuum booster.My choice was I located a 72 Cutlass disk brake set up from one of the guys in the Classic Olds Forum I also bought new rebuilt GM calipers and new GM rotors. Now on the 64 pro-touring build currently under construction it has the B-spindle upgrade with 91 IROCZ-1LE performance package rotors plus a ton of other components to make it work, but it was fun.

Hydraulic assist will solve all your problems, lots of older gm`s used it, parts are cheap (used) trouble free. I think there was a chit-chat here awhile back.

"Postcar" is there not a electric vacuum booster that's not to difficult to plump into these old buggies off the Cadillac Northstar?, They would be like you said a dime a dozen. I am going to watch this thread because on the the 64 build, I may do what's going on here. This is good stuff.

If memory serves me, the electric booster, is just that. A booster that kicks in in emergency situations, like stalled engine, low vacuum situations. You need a vacuum reservoir with it. I don`t believe there for constant use. I know they sell electric models, question is, do they work? Hydroboost does work, and there in the junk yards. Maybe someone can find that thread on the hydraboost here, I`m almost positive it was here. There a super simple install

One other consideration, the big cars that used the elec. vac. pumps WEREN`T running 65 amp alternators. Even IF you update your system you stand a good chance of over taxing your electrical system. Just let your steer pump do the work, get rid of the big vac booster, save some room.

Ok... so could one get this hydro-boost from Napa...

www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=NBB527200_0136023361&An=599001+101983+50052+2052006&Ar=AND(P_RecType%3aA)

... it's NAPA part no NBB 527200 ($177) if the link doesn't work, add their existing master cylinder and two hydraulic lines (one from the pressure side of the pump, and the other to the pressure side of the power steering box), and that would work?

It appears that the hydro-boost they list includes the mount to the firewall, and a pedal rod. Hard to say if the rod is the appropriate length, but I searched this part based on an '83 Delta 88, so maybe it's close.

note: it looks like there are actually 3 hydraulic connects on the unit... hi-pressure in and out... the third being a low pressure return. So what is the method to connect both the low pressure return from the boost unit AND the steering box back to the power steering pump?

I know nothing about the napa booster, but first look tells me there`s no accumulator on it, no master cyl. Forget the money aspect, so often people are so wound up with dollars, first and foremost should be quality, performance, and dependability.
There are 3 lines to the booster. The way it goes, pressure from pump to pressure "IN" on booster, pressure "OUT" from booster to pressure "IN" on steer box, return from booster tied in to return from steer box using either a "Y" type fitting or a directional flow "T" terminating at the steer pump. Simple as that !! Push rod is adjusted as it would be with any other install. These units aren`t magic, all they do is direct fluid under pressure to either steering or braking thru a diverter valve, the amount of fluid or force being directed(or diverted) is controlled by the travel of the brake pedal. There`s so little fluid needed to activate the master cylinder that there is seldom any steering loss, even at pump idle speed. But, and here`s where the accumulator comes in to the circuit, being that the accumulator is just what it`s name implies, it accumulates and stores energy, ONLY when brakes are applied the accumulator releases it`s stored energy to keep a constant pressure in the system so no pressure drops can be detected. Cool shit don`t you think. Now in case your engine throws up all over the race track you will still have max braking pressure because of the accumulator charge.

The original G.M. is the way to go, period !! In my opinion. And it`s not because it`s cheap, it`s because it`s hands down BETTER.
I called my local junkie, he runs a medium size yard, been doing business there for almost 50 yrs, he says he`s got a few out there, 65 bucks booster w/ master, 85 bucks booster, master, pump hoses and any brackets that are with it. (remove yourself)

don`t know if in this instance you can classify using a USED, factory, hydraboost from a gm vehicle, being "on the cheap" These are quality built pieces, designed and engineered for long life with a proven track record. In this case, I myself, wouldn`t hesitate to opt for a used original equipment hydraboost over an aftermarket replacement. And the decision wouldn`t be monetary .
X2 GM parts are some of the best. When I went to Main street Auto to get the calipers for the 67, ( as most auto supply houses) they get several rebuilt calipers in everyday. I told the gal behind the counter to let me know when they get a pair of rebuilt GM calipers in for my application. Took about 2 weeks before she found a pair that came in. She loved the Starbucks gift card!! On the 64 with the B-spindle disk brake upgrade everything is GM. ( Spindles came off a 91 Buick estate wagon)

I guess, depending on how marginal your vacuum is, the canister may be, at best, a band aid. If you think of the vacuum canister as a water bucket, and your vacuum line as a garden hose. Depending on the size of the canister (bucket), the amount of vacuum available (pressure in garden hose) once the brakes are applied once or twice in succession, how long is it going to take to replenish your vacuum (fill the bucket with a slow running hose) to a level to operate the brakes to FULL potential? With a hydroboost there is no re-fill or wait time, brake application pressure is ALWAYS at full potential. Now I`m guessing if your friends car is operating as designed even after several rapid brake applications, his vacuum was quite high to begin with. The hydroboost is a fail safe way to eliminate LOW vacuum conditions. Never said it was for everybody.