[502ms]

You know, if you go 6.0 LQ4 or LQ9, you have a whole lot more available to you. From my research, you can get to 460-480 RWHP with LS6 heads and headers on that setup. My 6.0 is being crated up and shipped to me now. I know it is going to be WORLDS better than my 350/TH400 which at best gives me 12mpg with 3.73 gears. I am moreso looking forward to that kind of power in my lightweight stepside. I am putting in a tko600, so fun factor is imminent.

To answer your question, that is what I would do. Don't waste time on a 5.3 or the 454. Don't waste time on carbing it. The EFI will save you on gas, and if you get the 6.0 and modify just a tad, you can really haul @ss. Bonus. Plus if you get a wild hair, supercharger kits are available that add 150HP+ to your setup.