Ok, I'll get beat up here.:D lol. Axle is out, 12 bolt, posi, ect. While its out I might as well change over to disk, Heres the dumb question, Has anyone done just the rear? because I just put all new front drum stuff on last late summer and was thinking of leaving it for now and just doing the rear. Question #2. Took the axle to a jobber for a rebuild and want him to do a freshen up ect. Now if he buttons it up, axles in, oil in, ect can the conversion be done without removing the axles for the backing plate assemblys? Or should I have him get the kit and do it before he buttons it back up, or can backing plate/anchors be installed with out removal? and what else would need to be done? Booster change? Master cyl change?

kind of odd but here is my .02
think the axles have to come out to get the new plates on. may want to get the kit to him before he gets done with it.
think if you have to change the proportioning valve but have never heard of one for your direct application. you may can use a disc/disc type but go with an adjustable type valve in the line (wilwood?) since this is an odd setup that am sure will have some strange front to rear bias that the factory type valve cant account for. the master cylinder - would use a version similar to a later model chevy truck (70's) with manual disc brakes.