well, if you dead set on a performace motor, and getting another motor is an option, why not build a perfamance engine, pull the numbers matching motor out, and save it. and if the time comes to sell that truck or whatever, and having a numbers matching engine will boost it's worth, you can just drop that motor back in.
whats it take to pull the motor on these trucks? ten minites
oh wait...i forgot you had a/c