You may not have enough fluid displacement for all the cylinders in the braking system. I believe that's why you went with a larger bore master cylinder. Problem is, the larger the master bore, the harder it is to push the pedal and get enough force at the braking cylinders. How large are the pistons in those calipers. Did they come off a power equiped Ram? Rule of thumb is if you take took the calipers from the truck you should have taken the master as well even if just to measure the stroke and bore. If the truck was power boosted, you should have taken that as well. Some brake components just don't mix well, but when it's engineered as a complete system you know it'll work. Where was the pin located on the truck brake arm in respect to your brake arm. Your pedal ratio may be way off. Did the truck have disks on the rear with large pistons? I took a complete hydro boost system off a 2002 GMC 2500 that had disk up front and drums out back. Other than a few little mods to mount the system on mine, when all was said and done, holly sh*t, what a braking system. If the pedal bottoms and you don't have positive braking, re-bleed the system, run the rear shoes as close to the drum as possible ( the residual valve is a great idea and belongs as close to the master as possible), install a manual proportioning valve and bench bleed the master again. Using the prop valve, close off the rear system completely and see if braking improves. If it does then your running out of fluid volume. If it's really hard, the master bore is too big, 15/16 is about right for power and 3/4 for manual. 1 1/4 is a master in the hydro boost style or a damn big vacuum booster with a long pedal attached to it. Look online at pre-engineered systems and see what components, their bore, and stroke and compare them to what you have. Go back to that truck and measure for pedal ratio and brake arm length. All will be revealed after a bit of investigation.
Thanks KingFish
