Is there a such thing as a survivor class for ATCs like there are for old cars?

[Legbah]

My '85 atc70 is all original but it is pretty worn. There is no doubt of it's originality but I had to make a decision, replace worn parts or limit it to little use and use it mainly for display. So far I using it for display and letting my son ride it about twice a week on a flat sandy track. Here's my problem, the carb is worn out and some very amatuer mechanics have tried their hand at maintenance and obviously boogered up the head. They stripped the spark plug hole and bored it out to a D size instead of C, stripped the threads in the intake mount and bored them out to 1/4" instead of 6MM. With the exception of minor wear the bike looks good but the engine with worn out Carb backfires when it's cold. The carb was extremely screwed when I got it and would only run with the choke on, the guy I got it from thought he had a 110 head on it but I guess it was already bored and tapped before he got it, becase it is the original 72cc head. Timings have been adjusted, points replaced and adj., the cam timing has been adjusted, and carb rebuilt 3-4 times. Any advice? Anybody think it's not worth it and I should make a mod from it? Is it a survivor?

[Legbah]

PS. cranks first pull and runs with no problem, idled a little high though and I think it's because the carb is worn out past the ability to fine tune it. All responses welcome even the rude ones.

[Wastegate]

Rebuild/replace what you need to and ride the crap out of the little bugger, There are quite a few around and the only way it would be not worth riding is if it was something rare like a 83Xmas special that was in original unmolested condition. But seeing as this one has been messed with a little I would just fix all the little things and ride it..