This is interesting. As a body tech and old car lover i am faced with this dayly.
Couple of things I though of is, 3m weld through primer, heated and not( have heard adhesion is poor until heated ((around a weld area)). An epoxy primer(DP50) over an acid etch or a metal treatment, will...
being such low miles I would kept the paint but maybe have it buffed out by a good body shop or detailer.
A high quality paint job is so much work, I just finished a 84 GN at work(about 200 hours @ 42.00$ hr plus parts and materials) completely dissasembled car striped to metal painted apart...
70-75 works best. With todays paint the car should not get below 60 deg for the first week and a month for best results. Remember to use proper hardeners and reducers for temp and humidity when spraying. Don't forget to protect your self Paint is very nasty stuff.
TimmyP