What is your definition of "fast"?
Do you mean off the light? Do you mean stump pulling torque? Do you mean roll-on acceleration? Do you mean top speed?
If you are looking for "big power" then you should have gotten a Corvette.
If you are looking for top speed you should have bought a Porsche.
If you are looking for a great engine that pulls hard, is reliable and sings at high rpm, then the S50B32 is a great engine. The S50B32 in an E30 is a near perfect package in terms of weight, balance, and handling. It is a setup that allows the driver to experience driving in it's purist form without traction control, steering assist, or any other electronic "nanny" that all the new cars have.
With regards to your brakes, if you want a definitive answer, Tilton has great customer service. If you provide all the details of your set up ie. weight of the car, caliper piston size, wheel and tire size etc. they will tell you exactly which master cylinder to use.
It's interesting, I have the same setup as you do. When I first drove it I SWORE it was too hard and not effective at all in terms of stopping power. I really wanted to buy smaller master cylinders too. I spent a lot of time talking to a lot of experts like Lee Vuong at Massive Brakes. What changed everything is once I took the car to the track and drove it the way it was supposed to be driven, braking very hard. After that experience it seemed to be fine on the street and I have absolutely no concerns or issues driving normally on the street. I think it's partly a matter of re-learning what we feel is "normal" in terms of braking and pedal feel. There is no such thing as feathering the brake pedal when it's a manual setup. It always requires firm pressure and more of it. I also strongly suggest you try a different brake pad. Using a pad with a harder initial bite will make your braking feel more effective at lower speeds.
Let me know how it goes and good luck.
Targa Newfoundland - It's about the Drive !