S10 Swap how to

[dsraven]

the booster to master pushrod gap could change since you have installed a new master cylinder, correct? not everything is equal and built exact so it is one thing to check possibly. while checking stuff, ensure te
he pedal to booster pushrod has some freeplay as this can mss with the booster operation if the valve inside the booster isn't centered. how do the calipers look. you say you replaced the rear wheel cylinders but have you checked the front calipers and their moving parts to ensure they are not getting hung up or are partially siezed? a good indicator of this is a set of brake pads that are worn more on one pad than the other. if the caliper slide mechanism is not allowing the caliper to slide then that could mess with the pedal feel between boosted or manual. another question for you is whether or not the master cylinder you removed due to an internal leak causing the slow drop to the floor, did it also leak some fluid out the rear of the master where the bore is? if so, some fluid may have made it's way into the booster and could cause problems. is your booster a dual diaphram type or a single diaphragm? singles are usually a larger overall size.
I removed a booster once that drained quite a bit of brake fluid out of the vacuum check valve port. this was caused by a leaky master cylinder at some point.
here is a link to some basic vac booster diagnostics.
https://axleaddict.com/auto-repair/B...-Booster-Check