Evan, not sure you might want to ask Lambs but I've been thinking about going down the R31 rear end set up it's just that I've been getting differing advice.
Lambs. I've checked out a few R31's and it looked like a bit of a pain to get the brackets off. Once the calipers and discs are pulled off how hard or rather what else is involved to get the brackets off?
R31 rear cals fit under 14" rims (only Silh's and Ti's had 15" rims, all the rest used 14" + all used the same brakes)
Getting the brackets off is fairly simple. Once the cals and discs are off, you'll see 4 nuts behind the axle disc flange. Those nuts secure the wheel bearing retainer (ie hold the axle in place) as well as the brake backing plate and the brackets, which simply slide over studs. Undo the nuts and pull the axle out of the diff housing. Once the axle is out, the brake backing plate and the bracket simply slide off. Sometimes the axle can be difficult to budge, esp if it's been in place for awhile, but a bit of gentle 'persausion' usually works.
As to price, I haven't checked in a long time, but I'd guess a place like Pick-a-Part would want around $30/cal