4 wheel disc troubles

I could be wrong, but I think A body power brake master cylinder is 1&1/32" because of the linkage setup required to raise the booster up to clear a V8 valve cover. It may have something to do with that. Manual disc brakes do not have this linkage. This may be part of the reason why those use 15/16 bore master cylinders.

A hold off valve going to the rear brakes may help keep pedal pressure up without multiple pumping. The fluid moves very little if the pads are in very close contact with the rotors.

The Aspen booster setup I believe is bolted straight to the firewall without the additional linkage to raise it up to clear like an A body. I dont see F body specs in your manual pix.

Fyi 15/16" is the same measurement as .937" it's just in decimal and not fractional.