I also wanted to state that I'm almost in the black as far as selling things off the IRS goes.
I've sold both axles, one knuckle, the rotors, and a tie rod, and I'm only $150 in the hole. Even if I don't sell anything else, $150 for a cobra pumpkin is pretty damn good!
Hopefully once the rest of my R200/ 280z stuff sells, I'll be ordering the backing plates, strut tubes, axles, and driveshaft. If I play my cards right, I'll only be into this whole conversion for about $3-400. Granted, I had a lot of money in other stuff in the rear to begin with, so I wouldn't count on anyone being able to replicate this exact setup for the same price. I'll post a spreadsheet when I get it all squared away to tell the true cost. However, if you do your shopping, it could easily be just as "cheap" as an R230 swap and billet things, with a better outcome, IMO.