Regarding the Ford 6.0 - I have a 2006. It's VERY well documented what goes wrong with these engines and what you have to do to bullet proof them.
Yeah I know, we found a 2004 F350 DRW Crew Cab with 82000 miles that has lived a garaged life and only towed an amateur race car team around. $18,000 couldn't pass that up. I'm fortunate enough to have a master mechanic as my co-worker and drinking buddy, so I'm in a good place. Plus I grew up with Land Rovers, so I don't care how bad the 6.0 gets, it cannot be more of a maintenance hog than a Landie. I'm also fortunate enough to have the time/resources to throw into this truck. So we're willing to gamble a bit on the beast. If it fails, we can re-address with a newer F350 with the 6.7, but I think this truck will outlast me.
I'll email you tonight while I'm suppoesd to be "working"