I was looking at swapping out the 3.4L on my '91 with the 3.0L.
The engine swap itself wasn't bad, but the wiring harness had to be replaced. You could either make your own or buy one and it wasn't cheap. Then you had to address the hood clearance, and do some custom welding on the manifold.
Many people did it, which is why there was so much information out there about it, but in the end, I decided against it and sold the 3.4L motor to someone. I really wanted a Toyota pickup with 190HP though.
