I've helped someone do it from the bottom for a bit, he did most of it. It all depends on what you have available, workspace, etc. You have to be able to lift the front end of car up fairly high.
How many miles on that LS1?
2001 Trans Am WS6 A4 - Pewter - GMMG/Madhammer w/ Bullet Catback, Lid, Tuned by Frost
2007 Acura RDX SH-AWD Turbo - Wife's Car/DD
1994 Camaro Z28 A4 - Dark Green-Grey Metallic - SOLD
1970 Camaro Z28 A2 Clone Project (0rwhp) -Primer