I would talk with a truck sales guy that really understands specing. I have made relationships with them for the brand I use to the point that I know every option that is available. These type of things are getting to be pretty well handled by electronics. I have trucks that cut the PTO off above X mph. Also trucks that auto shift the truck to neutral while a function of the PTO is used in conjuntion with the brake. Believe it or not, the engineering department of a real vocational truck MFG has considered this stuff. I know the word engineer makes most of want to run..... SunsPSD is a guy who has experience in this field, might PM him. And hey, I'm still running a 6.6 ford everyday, I think it is actually a pretty good motor, alittle under powered, but hey it has a P-pump and a T04 turbo on it don't it? Is yours intercooled?