Id guess this will be trail only? Id consider the GM gen III family of motors. You can pick up a low mileage 5.3 with harness and comp for under a grand in most cases. factory with 285 hp and about the same tq, awesome reliability, can be ran at steep angles and parts can be found at any auto parts store which can help when your 500miles from home and broke. Get in contact with SLOWROCKR on here, he can set you up with a modified harness and flash your Pcm as well.
If you don't go with the Gen III my next suggestion would a sbc 350 not 305 w/ a turbo. Now that would be sweet. The 3.8 turbocharged are very sweet little motors as well.
Good luck and let us know what you end up with.
86' K20 350vortec /700r4/208 3/4 ton ,4.10's highsteer w/ hydro assist, 12k warn & 40's
01 Z71 A set of 49 Irocs and Big Plans
Wanted: 2 front rockwell's