It's not pressure you need to worry about, it's f/r bias (of pressure) and fluid volume displacement that needs looking at. The pressure is simply proportionate to applied pedal effort.
The stock m/c works* with most 'big' calipers because the orignial drum brakes have no self-adjustment to compensate for wear. They rely on the long stroke of the m/c.
You will be able to tell if your m/c is big enough if you bleed the air out by the pedal method.
* 'works' in terms of volume but not necessarily in bias
The sure way to know if your system works as a system is to have them tested on a plate brake tester, just drive on, hit the brakes and let strain-guage technology interpret the reaction of the road.
I'd be looking at the m/c off a T2 before that off a 944
Matt
stock '03 m/c with 40/36mm and 30/28mm 951 Brembo's + an AREX