You could always go blowthrough (carb). Your EFI setup is the limiting factor. I have seen a few 5.3/lsx swap turbo setups on your style truck though. If you are going to do a new EFI system, you may as well do a 5.3 swap. Heck, even a 4.8 can make alot of power with a turbo (~400whp at 6psi)...