drivetrain time

[LONGTALL]

the axles are done and now time for the drivetrain. looking for opinions for engine and transmission options. the transfer case will be the stak 3speed mini with 5.22 gearing. the engine and trans from chevy trucks i can get from different places.
my different options/thoughts:
1. newer 5.3 with 4l65e/470e
2. pre 06 6.0/4l80e
3. 07 or 08 6.0 and use an older 4l80e or 4l60e
i can get 5.3 easier and cheaper then the 6.0 engines, but concern on power to get the job done. it is all going into a scrambler, full steel body, one tons 41 iroks. the wiring is coming from speartech; heard get things about them.