If you're never worried about selling it and just HAVE to have a diesel, I would be looking at a MERCEDES OM606 turbo with a OM603 pump swap. They're good for around 180HP if you max the stock OM603 pump(or you can have the OM603 pump worked on, and go upwards of 400HP I believe on a stock bottom end), and can turn up to around 5200-5500 RPM's which makes them good gas engine swap candidates as they can work with most drivetrains geared for a gasser. The downside is the oil pan on them is pretty large because of how the pump is mounted to the front lower part of the block and driven by a chain. The downside is, if you ever decide to sell it, you could be in for a NIGHTMARE! It will not pass emissions ANYWHERE, and some states would actually come after you and make you make it emissions legal or make you buy it back but keep the truck to destroy it(YES, this HAS happened as it is against federal law to build a non emissions compliant truck. It is wether or not the state enforces the federal laws or not). Personnally I wouldn't even consider diesel swapping a truck that new as making the electrical in the truck work afterwards won't be the easiest of tasks, and if you want it to look clean and not just rigged in will be ALOT of custom work.