Brake pedal is really stiff

you prob have a combination of small bore, 7/8 wheel cylinders, where 15/16 is avail, and a larger bore M/C.. where a smaller bore is avail, . . that'll give you a super hard pedal..

I saw several posts asking you to measure m/c bore size,, did you ever measure it??

and for the heck of it,, pull a piston outta your wheel cyls.. I bet they're small.. jmo