I try veeeery hard not to jump on people on here who sometimes ask some pretty crazy questions but on this one I just cant help myself ........ so sorry before I even start.
Your a diesel tech at Ford, and you have to ask us if $500 is a good deal for a straight, good condition F450 cab chassis but that needs a HPOP repair?
Dude, if you don't know then you should quit your job and go sell shoes!!!
OK, so since you were looking for advise here it is......
Go ask one of the salesmen up front to look up and tell you how much its worth.
Then, get on your computer and go visit, Truck Paper, Ritchie Bros Auctions etc etc etc to see what they have been selling for, also check out Craigs list, EBay as well.
You should already know what the repairs are going to cost.
I would be very surprised if you couldn't get $4k or more for it (running that is).
Anyway, sorry again .....so go give the guy his $500, get it fixed and make some money!!!! Then send 10% to us here for beer money.