Newbie Us Van

Good day people I am still a little light at the Us van sky for this is my enthusiasm for this kind of vans very strong. I am through unf by a USA Freak =) I have already received many useful infos from you like zb KLR Euro 2 and and and and (thanks for it ) only one question is still open: I want to put a used van ( G20, Vandura or Econoline) just I would like to know what so en 5-6 L V8 engine can withstand at KM / Mls running power. can I get one of the 150 000 KM has run=???? I would be happy about an early answer mfg Tyler