One thing I found about mounting under the body on the frame is that you will need to pump more often even if power assit. the fluid rns back and even a residual(sp?) valve does not take away completely.
I don't have that problem, and I have installed two different masters and boosters under the floor, both with disc brakes and 2lb residual pressure valves, absolutely no need to pump the brakes. The systems I installed/put together, if you wanted to try it, would send you through the windshield with the first application. I would be looking for mismatched parts or to small a MC bore if I had to pump the pedal for the brakes to work well.
Grigg
