Did I miss you saying your truck was all ready a diesel? I think I had the money I would have made the jeep into a diesel. I really want a diesel truck.
You may also want to think about carefully about the time and costs associated with doing an engine swap. I always have to tease my BF about my engine swap, he said he would have it done in a weekend, well it ended up taking two months all together. Now he is in the process of switching out his wrangler from the 4 banger to the straight six and it's going on about two months now too for that project. You may be better off getting a newer truck with a better engine in it.