I also have a 55 2nd with the 248 and was asking myself the same thing. I went with rebuilding the 248 and haven't had a single regret. For me it came down to will I drive it more if I went sbc or some other arrangement? The cost and can of worms the engine change would have caused made the answer easy for me. But one thing that has been repeated on several occasions on this site is, it's your truck, do what you want with it. Good luck!
