5.3 L33/Lm7. Steer me in the right direction

Hello all... Well I'm making the conversion finally for my Buick Grand national. The Buick Stage II parts are getting hard to come by and $$$$.. Alot of the guys are going to the 5.3 in there buicks with great success almost bone stock. Now for my stupid questions.. Which motor is best for turbo application? L33/Lm7? My goal is 800-900 rwhp. Not sure if this is a good set up... L33 with Rods# CSC6125DS2A2Ah, pistons# K474M96, stock crank. New cam but not sure of a size yet.. I'll take all the advise I can get! Chevy stuff is new to me, but can build a Turbo Buick motor in my sleep.

L33 (5.3 HO) - Aluminum block, better flowing heads, 9.9:1 Compression
LM7 (Basic 5.3) - Iron block, 9.5:1 compression.

Stock 4.8 with cam and heads can handle 27 lbs for a limited amount of time. One of the magazines did I budget build turbo with one from a junkyard and got over 1200hp to the flywheel. I'm sure it's been posted here before but the link is below.
http://www.hotrod.com/techarticles/h...g_bang_theory/