Hi Darren,
You really ought to consider putting a Caddy 500 in your truck. I thought about building a BBC for my Blazer before I did the Caddy thing. I don't regret going Caddy at all. The 500 can put out major power and still weigh just a little more than a 350. They are tough old blocks made with tons of Nickle and can be found in RWD Caddies from 74-76 and FWD Eldos from 70-76. The Eldo engines will have the all important rear sump pan for your swap. Let me know if you want to go that direction. In the meantime, check out
www.cad500parts.com and
www.500cid.com . Good luck.
Sincerely,
Chris
here's the 500 in my Blazer: