The problem with the truck (and most car ) replacement master cylinders is they are generally 1 1/8" bore. That's fine for power brakes but OP picture indicates no power boost. 1 1/32" or 1 1/8" bore will give very hard pedal with no PB! The 15/16" bore will give better stopping power although with a little more pedal travel. I believe Dr. Diff is the only source for the 15/16" bore unit.
I have the aluminum 15/16" bore on my 72 Demon (drums with No PB) and even with the adapter block the pedal returns all the way with the standard push rod.
