Hi and welcome to mightyram. Yeah, buying a vehicle that the owner smoked in is a different kind of challenge to fix up. The up side to this is it's only a single cab truck and you could take everything out without too much grief. The rest of your MM looks to be in great shape both body wise and cosmetically overall. Take your belts out, get some premixed spray on sugar soap and soak it in with everything full extended and nail it with a pressure cleaner. It will get everything out of the nylon weave. Let it dry and give them a coat of silicon spray. This will restore it's colour and pliability + make belt retraction smoother. If the front end is all original (which is likely) I think you're in for a full rebuild. Sounds like the rest of it is basic stuff (if you don't have bad crank seals the other leaks are easy fixes).