Well i plan to get modern rims, 17 or 18. And you dont think the price difference between front & rear disc kit, is about the same as front kit and new drum & rotor ?
this changes everything. going to a modern rim basically requires the swap to be BBP.
the front is not terribly involved, kits and parts are out there making the job straight forward.
out back it's not a simple process of just a new set of drums. you'll at minimum need to change your axles, which that's a whole ball of wax. better to upgrade the entire axle assembly.
while you could probably track down a 7.25 rear in BBP, my advice would be to upgrade to another axle-- 8.25, 8.75, 8.8 or 9" (gasps, clutches pearls)
at any rate, going discs on the rear isn't going to gain you anything that drums don't offer for street driving.