If you are really interested, contact me offline. I know of several places to look that each list a number of coaches for sale.
The rear-end project took me a little over a week for the big work, working 12-hour days. I took a month off from work last year, and this was one of the projects I took on. I then spent another week doing a bunch of little stuff associated with it. I am still chasing body leaks, though, and won't do the interior carpentry until those are all repaired.
Regarding what these really cost, I've developed a theory based on a lot of successful GMC ownerships of people I know. A good GMC coach costs $25-30K. You can buy them in "running" condition for as little as $5000, but you'll end up spending the rest making it reliable and decent-looking. I'm into mine for about $14K at the moment. I've redone the house electrical system, replaced the generator, replaced the fuel tanks, done a chunk of engine work (headers, new carb, new distributor, many new instruments), and replaced a lot of the air suspension (new bags, new shocks, new compressor, many new lines, etc.). The brakes and front ball joints had already been replaced. I've had to redo the plumbing drains (which involved dropping the black tank--a fun project), and now I'm redoing the leaky refrigerator vents.
By the time I've had it painted, replaced the wheels with Alcoas (the original 16.5" tires aren't as available as they used to be), finished the interior, rebuilt the engine and transmission, and redone the rear suspension pivots, I'll be into it for right around $30K.
That's about half the price of a chip-board box on a van chassis that will be worthless when it's half as old as a GMC. At least half the GMC production run of 13,000 is still in use.
You can also buy them completely rebuilt with all new stuff from engine to macerator, in like-new condition complete with a warranty. They run in the $65K range in that sort of condition, which is competitive with new motorhomes that don't drive or ride nearly as well and that has a much cheaper interior.
You are, of course, a perfect candidate for GMC ownership. One of the popular mods is to replace the Olds 455 with a Caddy 500 from one of the front-drive Eldos that used the same transmission. Right up your alley!
Rick "getting ready for a short trip next week, in fact" Denney