Jerry, thanks for the input. You've given me a bit to think about.
Longbed, I like the idea of the Cummins but I think I'm too much of a purist especially since my '58 is very clean and solid. On the "TRUCKS" TV show, they dropped a crew cab longbed of a "different brand" truck onto a modern pickup frame with its diesel drive train. I wish they had used a Chevy or GMC instead of what they chose but it was pretty cool anyway.
Steve