The 2JZGTE or the 7MGTE Toyota inline six turbo motors are very cool but they need a custom adapter bellhousing to use the beefier "R" series, 5 speed, 4x4 transmission. <IIRC> People with big tires and turbo inline sixes break Toyota 8" diffs as well.

The Painless wiring harness can be bought for a couple hundred less than the list price if you shop around.

In Australia they have a heavy duty 5 speed (bigger and beefier than the "R" series) in the Landcruiser and there are adapters to put a Toyota I-Force or Lexus 1UZFE V8 in front of that. There you would have an all Toyota swap!