I couldn't fit the stock clutch fan on my 90 runner. I didn't have a body lift, not sure if that made the differance. I couldn't move the motor much further back than I had it. I used a puller fan and the stock pusher fan with the V6 radiator. It would get hot sometimes but recovered quickly. It could have cooled better that's for sure.
I used the howell harness and liked it. The easiest way to use the factory guages is to adapt the sensors over and get yourself a yota wiring diagram to find anything else you'll need.
Depending on where you're at the newer OBD2 motors could be more of a PIA because of smog laws. You have to have more parts from the donor vehicle.
I also adapted the gm fuel pump into my stock tank, but it was very easy the way I did it.
I had a '93CPI vortec. The power was great but aftermarket parts availablility was very limited. If you think you're going to want differant intake, exhaust, cam etc the throttle body motors have way more aftermarket parts.