Yeah I know it doesn't seem like much of an upgrade moving to an older truck with a smaller engine.
A couple of years ago I bought a 2wd '98 XLT supercab OHV 4.0 that had been neglected but not abused. I fixed it up, cleaned and polished and fixed/replaced all kinds of crazy stuff in the process. My son has been driving it ever since. It still has some issues with random dash lights but it runs good and serves him well driving to school and to work. It has ~98K miles.
Tomorrow we will be taking possession of his grandfather's 2wd '97 XLT supercab 3.0. Aside from some body damage on the bed it's a cream puff. Always well maintained etc. It has ~ 90K miles.
The hope is that the years of pampering and and professional maintenance on the '97 will pay off in the form of a more reliable truck for the future as my son will be starting college this fall and we need it to last for 6 years or longer if possible.
Also that 4.0 OHV is tough on gas. Here's hoping the 3.0 is less thirsty.

 

The 3.0 is a little less thirsty than an OHV 4.0l but nothing to major their but as far as reliability and lifespan the 3.0 will run circles around the 4.0 in that category. The 3.0's are famous for 3-400,000 miles with very little maintenance or trouble. My advice at 90k id go ahead and swap water pump and timing cover gasket about $100 in parts but it will save your head gaskets and make sure to stay on top of oil changes and coolant flushes then six years will be easy to get out of that motor probably more. Id also swap camshaft synchro if its never been done that and coolant are the two weak spots on these motors keep an eye on those and your golden.