The Cummins is a great motor. A bit pricey and heavy. Plus you have to be an expert to rebuild one. I think a turbo 292 or 250 would be a great idea. Heck the cummins would be a dog with out the turbo. You know the six can get things moving ok, but when you are at highway speed and start going up hill, you will be really wanting more power. Thats why I think a turbo would complete the picture. Just my 2 cents.
-Dave