Please don't take this too seriously as I have major doubts about my own knowleadge.
First of all, a 265/283 was an option for your truck right? Therefore a small block swap should be a no brainer. Second, didn't chevy make a 350ci diesel that was based on the gas-powered small block? It might be worth looking into, but I haven't heard the best comments about this 350 diesel. I'm sure someone will correct me if I'm wrong.
