I wouldn't go that route. You need the ECM for the engine and depending on the trans you use you may need a pcm for that as well. The wiring is complex and the ecm for the engine is very expensive. However if I had your money I would throw mine away. There is nothing more reliable than a 12 valve Cummins. Choose wisely.
If your into electronics and less dependability then go the 6.7 route but the 5.9 is about as dependable as they get, and you can make power very affordably without electronics. In my opinion if this is a primarily for towing or going to do a lot of towing Id stick to 300-400 hp. any trailer requiring more hp shouldn't be towed by a pick up. The engine will hold up but the Trans and diffs (pickup size) will take a beating as well
Another thought to add. I had an '83 Crew Cab I swapped a '93 inter-cooled motor into, turned up the pump timing, added some big injectors and other minor mods got very good fuel mileage and power, I replaced that truck with an '01 24 valve (electronic motor) similar power less fuel mileage. Not to take away from the knowledgeable members here but
www.dieseltruckresource.com is a great site for such projects.
