Looking for Guidance

[L31MaxExpress]

5.3L is a boat anchor without boost, especially with a 4L80E behind it. Pontiac 400 makes loads of low-midrange torque, even a stock smog era unit.

 

[Erik the Awful]

There is a TBI fed 500 cadillac in a member of this groups truck.

There were kits for this twenty years ago. It's a great truck motor, but I wouldn't do it, for the same reason I wouldn't swap in a 400 Poncho motor. There's a lack of parts availability out on the road. If you break down in Nowhere, Kansas, you're going to wait a couple days for FedEx to bring you a water pump or whatever. Save that 400 for a Pontiac build or sell it to someone who needs it. I'd put a 350 or 454 in your truck, or do an LS swap if you feel froggy.