The bigger the bore, the higher the pedal effort for manual brakes (and longer required pedal travel -- but long pedal travel can be caused by other 'errors' in the installation). Would be the same rule for PB also, but you might not feel the difference as the booster might mask it.

I put manual DB on my 68 Fury and used a MC from a mid-70s 1/2-ton truck with MDisc. Don't know the bore, but I know it's on the smaller end. Same pedal feel as MDrum but significantly improved braking.

I feel there's a typo or some add'l info missing in that chart above. 1-1/8 is the largest bore, and has always been used with PB (I don't know what that taxi reference is about). The heavier the car, the more crucial the bore size toward pedal effort. A 67-70 A-body could probably use the same bore for both PB and MB, but a heavier car will show excessive pedal effort if the bore is too big.

Edit - that chart is showing where a particular MC was used, bu tit doesn't mean that it's the only MC used for that car - 67-69 C-body is an example of that, a 67-68 could have 1 of 2 bore sizes for MB or PB.