Thanks again for all the very informed replies. It means a lot
The only unique advice I can add is this:
Make friends with the WI MUD members on here... like in person. With the experienced eyes and hands of the MUD community, your rough idle can be fixed in an afternoon, rather than over the course of weeks. These are good guys. I'm sure the locals will help you keep your 80 on the road.
Now... post up some pictures. That way we can see what this beater looks like.