Already been mentioned but cooling system needs to be immaculate, check very carefully for head leaks and get them repaired ASAP if found, last thing you want is a slipped liner. (Good excuse for fitting a hi comp 4.6 though...)

The purchase price is a good reason to get one, but the city fuel cycle is abysmal. The country cycle is really very good for a heavy petrol vehicle, Gas isn't worthwhile IMHO unless you are fitting it to a Hi comp engine, and don't bother with vapour injection.

MAKE sure IF you are running gas, that you use petrol regularly. One of the drawbacks of the Thor engine is that it doesn't circulate fuel through the fuel rail so the injectors really suffer with prolonged LPG use.

JC