Shit, we're all wrong. Swap in a VW diesel and sell it for $14,000.
3RZ-FE 2.7L with a nice exhaust/header set up.
That's a stupid motor. Only a stupidhead would try and swap a 2.7 in.
If up to the fabrication task do a straight six of some kind; that would be sick.
What is the budget?
MASSIVE fabrication work here--the truck's front end simply isn't long enough. A V8 requires mounting the fan outside the engine compartment, and that's after moving the whole drivetrain backward a few inches. Your I-6 is two cylinders longer still--not a good idea, friend.