I think about an engine power build, but the more I learn the least incline I am. My take is; the most usefull and reliable power I know of at the rear weels from a 6.2 - 6.5 is about 260hp. (somewere in youtube they show a late 6.5 turbo+propane in the dino) at the wheels. Not bad but not sufficient to justify trouble and cost I would rather go with the cheap Big block gas, or if Diesel, a 12 V. Cummings and then "HOW MUCH HORSE POWER CAN YOU AFFORD?" would be the issue. Long run it would be cheper, more reliable and have more HP potencial. A used 4bt is another idea but I think that one besides havving the advantage of beign ligther would probably cost more becouse of limited avalibility. JUST ME BRAINSTORMING...