I'm also in agreement that a LSX block is neccessary. I have a friend who is running a 348 with 850 rwhp with a ECS supercharger setup.
I really like the new kenne bell supercharger.
http://kennebell.net/KBWebsite/SC_pg...s/SCCAM6.2.htm
They are getting 720rwhp out of a stock motor. Put some good pistons and rods in it, you will be fine.
Cam, there are so many out there, I've got no clue which is best.