While the logic is there of using a prop valve from a disc/ disc set up, I would say no even if the masters bolt pattern just happen to be the same. The reason is it is very unlikely that the masters pushrods will be the same length or need the same amount of travel. If wrong, you'd end up with brakes always partially on or a gap between the connection. Either way, the pedal action won't be right. Your sig says you have both, so some good old fashion measuring would be in order. I too have both, and while I'm not armed with numbers at the moment, I remember them being very different
I got one bleeder out and got a new caliper. installed everything pumped the brakes to push fluid to the rear and opened the bleeders a couple of times.
Seems beter I'll wait till a bud can come over and two man bleed the brakes.