need brake suggestion

ok so 15/16 or 1.0" does either one make a difference on the brake pedal feel, I know close to the same. I have a factory p/b unit, but not enough vacuum to keep working, added a canister and electric vacuum pump, feels like crap, almost a manual, rather it be that way and stop in my opinion. its a 318 raised compression, high rise air gap, with carb spacer, and 268/270ish mp 340 cam.... a/t with 3.50 gears. 28" tires. I also have to change converters. likes to drop out of gear rev up and goes, possible valve body issue. its a 1978/79 a999or a998 lock up model, planning on taking out and putting original a904 back in with a stall converter....@2000rpm.... thoughts?