you can build a damn quick 22RE for $3k.

you can barely get an LS1 engine for $3k in good shape... then you still need a trans ($1500+), and even if you got the engine with the computer/harness you'll have to have it wired and have the computer programmed to run without VATS and other things that won't be hooked up ($300+ for wiring, $200-400 for reprogramming). then you have to get it in the truck, which it sounds like you can't do on your own so factor in shop labor at $70/hr for probably a good 80+ hours of work. then add tons of smaller parts you'll need like building an exhaust, intake setup, etc etc.

see what i'm getting at? check out LCEngineering for some kickass go fast parts for the toyota pickups.