FWD cars generally have a diagonally split system so the proportioning would likely be incorrect. I guess you could get away with it but that's the reason not to use a FWD master cylinder on a front/rear split car.
I don't think the front wheel drive MC has anything to do with the braking problems I'm having. There is absolutely none of the original brake system left on the car. The front reservoir goes to a line lock then to a tee fitting then to the front wheels and the rear reservoir goes to an adjustable proportioning valve, then to the rear brakes. This K car MC has a 7/8" bore, which is the same as the Wilwood one it replaced and it performs exactly the same as the Wilwood one did. I believe the problem is with the pads and/or rotors. I either have the wrong pads or I failed to properly burnish the new pads even though I followed Wilwoods instructions on how to do that. There is a third possibility and that is that the Wilwood brakes simply do not perform up to par, which is something I have heard other guys say. No matter what, I have to solve the problem and I'm going to do whatever it takes to do it, even if it means ditching the Wilwood brakes.
