Yeah, I know I am a Ford guy

But I recently built a 400 SBC for my littlest brothers Chebby Luv after he blew the 350. Personally, if I had that truck I'd look for a good used 400, rent an engine hoist, swap motors and then put on add ons like a decent manifold and carb, headers, etc, etc. You can't not beat cubic inches unless you are willing to spend cubic yards of money.