I'm seriously considering doing a hydroboost swap because my 4-wheel disc brakes with 8" dual diaphragm booster and 1 1/8" Corvette style MC just aren't giving me the performance I desire. Even after bleeding, I can't lock them up on my best attempt to. What master cylinder are you using with your swap and are you satisfied with the results. What would you do differently with your swap?
Pedal ratio? Stock 57 manual pedal assembly? I feel the master bore is too large. A smaller bore will require slightly more pedal travel but with disc on all four corners that should be small. I would jump into a 15/16 bore. It will give a significantly larger increase in pressure to the brakes.
My Lincoln donated hydraulic booster and master was 1-1/8". But, the booster is nearly twice that of vacuum booster especially an eight inch. I replaced the OEM with a Wilwood 1-1/8" with no difference. Corvette 1-1/8" is a common, aftermarket size.
I have hydraulic boosters on two of my '57s with disc front and rear. Both have OEM, manual pedals with an unaltered ratio. I think it is more of a booster issue but it can be fixed with ratio change and/or MC bore change.
I just swapped it out with another 1 1/8" Corvette MC, vs swapping for the 1" Corvette MC. After bleeding forever and adjusting the rear calipers (Seville style that's fixed and needs ratcheting, I didn't know this until recently) it seems to stop better. Definitely won't lock up, but performs better than it ever has prior.
I'm chewing between the Borgeson box or the new electric assist steering. May go hydroboost in the future.
My hydroboost is from a '02 Mustang Cobra. It has the 1 1/8 which is larger than some of the older Mustang units. I believe '01 or newer on the Mustangs is what I was told I needed as the smaller was not going to be adequate. I'm happy with mine, took a few trials to get the proportioning valve set so the rears would not lock up first. Never really tried to lock them up after that.