So this is after a few hours in acetone! Should I let it continue to soak or do I risk damaging it at some point?
No more acetone! Your great find is close to turning pink. A zincoln is a zincoln. My next (and only) step would be verti care. Search this site for badthad. Congratulations for a nice find!
Looks a little better!! Like @Dynoking said I wouldn’t dip it any more. What ever was on there had a high acid content and there is no fixing that. Enjoy it for what it is!!!