Bob,
I have a 283 SB in my 55.1. The P.O. had put in the motor and left the original rear end in. At first it was great for putting around town and going to the store.
After a while I wanted to venture a little further away from home where more speed was necessary and now I am swapping rear ends.
I would go the V8 route, I think long term you will be happier.
However, it is your truck and no matter what we say, you go ahead and do what you want to your truck.
-Chris
