While I leave the 2.8/3.4 expertise up to EdMc and Jim, I will say that a) any effort and money you put into rebuilding the 2.8 can be easily put into putting a 3.4 into your Trooper and b) everyone I have ever met with a 3.4 swap has a hard time speaking for the smile plastered on their face.

The 3.4 swap is as close to a plug and play swap as you will probably ever see, minus a few things like drilling for the starter. But that is not a show stopper. Put the 4.3 TBI on top of it, roller rockers, a cam and exhaust and it will have plenty of power for your grandson. In fact, you may want to keep it yourself after that.

Good Luck,
Michael