"Transitional" setup

I want to do a drum-to-disc conversion on the Cuda's fronts (the Scarebird way, I think), but am sticking on the idea of switching to a 5X4.5 setup for wheel availability. Right now, I just need to get it driveable, which means I have to replace all the brake lines, and make sure all the cylinders / drums, etc. are okay (for now). So, without having to do the job twice, I think I want to set it up "transitionally" - i.e. all new lines, adjustable prop valve, new m/c for the disc setup (Will, say, a '74 A-body manual disc m/c be okay to use with my 10" drums until I make the switch to discs?), and, hopefully, keep the drums in place for a while. That way, when I get to the conversion I only have to re-do the caliper lines. Am I out on a limb, here?