Hudson,
Ralphy and the boys are right on -- you might try just fixing it up as is and driving it for awhile to enjoy it before you start doing things that aren't so easy to undo -- especially a rear end swap.
Remember, that ole 216 (or 235 for that matter) cranks out only about 90 HP. If you start throwing taller gear ratios at it (with a newer rear end), you're going to overload that old babbit pounder real fast. If you upgrade the rear end, you'll have to upgrade the front (motor). And once you do that, then you're talking higher speeds, so you'll want to (have to) upgrade your brakes, too, as well as your steering. It's one thing to go faster, it's another to go faster and live.
See where this is headed?
Putting diesel in it is a great idea, but then you have to upgrade the radiator, front suspension and also the brakes and rear end -- great if you want to spend the money and have the resources -- in fact I am seriously considering doing that with my ton and a half -- finding a Cummins out of a junked Dodge, but I am intimidated by the electronics and other mods I will have to make.
For what it's worth, there's an article in the Tech Tips section on just this subject (Restoring Big Trucks). Even though I wrote it, there might actually be something there you find helpful in deciding what you are going to do. Just use the menu bar at the top of this page, click on "Tech Tips" and scroll down until you find the article.
If you have any other questions, don't hesitate to ask -- we're all in this together.
Regards,
John
