***Quick Update***
I pulled the tank off last night to look over everything as much as I could. I wanted to do a compression test but turned out I don't have the appropriate sized socket to remove the plugs.
So here's what I found so far:
- The tank had gas in it which is my fault because I'm the one who used to ride it and parked it in the barn after college where the poor thing sat for 23 years. I emptied it but it looks like bad news in there. Lots of rust, but on the other hand no holes or weak spots as far as I can tell. Unfortunately there's a crease in it from when it fell over in the back of a pickup truck years ago.
- Mileage is 20,200
- Manufacture date was 2/75.
- It appears that there is no deep rust anyplace on it. Even the exhaust looks really good from the headers all the way through the muffler. There's a little corrosion in the battery tray, but not bad and does not appear to have leaked through onto anything underneath. Frame, swingarm, shocks, forks, fenders, hell even the chain guard, all have a little surface rust here and there but seem to be solid.
- The motor kicks over freely, but it has a head gasket leak that was actually always there as far as I remember
- Aside from replacement mirrors, it's 100% complete and stock. Seems I've had a classic barn find at my childhood home!
So I think I've made a decision. The bike is in way too good of shape (assuming that the motor isn't a major issue) and also has too much sentimental value to either sell it or chop it up and turn it into some kind of cafe/brat/whatever. I'm going to tear it down and clean, repair, replace where necessary, and put it back together again as-is with maybe a couple little mods, and then ride the hell out of it.
Thanks again for all the feedback and opinions and advice. I feel really good now about resurrecting it and getting it back on the street ASAP.