master cylinder for stock front disc + empi rear discs

[evilC]

Firstly what size is the Empi rear piston? The front if a 944 sliding caliper should be 53.5mm piston. The standard 19/19 m/c should be well up to the job if the bias front and rear are within reasonable limits . There should be no need to play around with m/c's and I wouldn't even speculate as to what will work without first assessing the front/rear bias.
Ideally, because of the rear weight bias the starting point is equal braking front and rear. This can then be adjusted to suit preferences and specific car mods.

evilC