My T-Bucket has much the same setup as you're trying to figure out. The MC mount is aft of the trans crossmember, the pedal goes up through the floor, pivots on a stud mounted to the frame, and actuates a pushrod which is made to reach the MC. If I wanted, there is enough room for a booster but the T is light enough and has enough pedal ratio that it is not needed. The setup I'm using is similar to this:
http://shop.spiritcars.com/Brakes/Br...y/prod_26.html