I have an aluminum lightweight master that I got from mancini @8 years ago. It failed and I need to get another. I have a 68 charger, manual brakes, mopar action 11.75 rotor swap front, stock drum brakes.

mancini website lists the MC, but two different bore sizes....what's better for my manual brakes, bigger or smaller bore?

for the life of me I can't remember what I bought so long ago, I have a vague recollection of calling them and saying "gimme" and I guess I got lucky. I will say that it always stopped the car very well...