This link might have some useful 351 info:
http://www.alternativeauto.com/water..._nut_bolt.html
The 7.5 rear should be able to take it for a little bit. I'd just run the 84's supension and not bother with upgrading it to an 88's. The '84's springs should give good weight transfer.
Also, I think you'll have to get a new hood with a ~4" cowl or cut a hole out in your current one. Or just run with no hood.
You can get a fiberglass hood with a 4" cowl here for $230 which seems fair.
http://www.cincinnaticomposites.com/cowl.htm