I like to keep an eye out for just this kind of deal... usually you can get a good deal on the motorhome. A few years ago I bought a 74 chevy pickup 2 wheel, kinda rough for $400. It came with a nasty camper shell on it, all rotted out. All the aluminum was pulled from the camper and sold for $80 bucks.
The contents of the camper... several tents, an old chainsaw,and a plethora of hodge podge tools were sold at the garage sale we had. Another $100. I then pulled the 454 and turbo 400 tranny to squarrel away. Took the truck to the scrap yard and got $200 for it. For about 2 saturdays of work it was like somebody just gave me a great spare 454 and tranny..... We live for those deals.
Its a 2 bolt, but will be great for street and up to about 600 HP... I may have the machine shop tap it for 4 bolts, I have some crazy ideas about a big block stroker motor.
Good luck and great find.
Gil