Does your S/O like your early A-body?
When we got engaged I made it clear that tinkering with old cars is my thing and that if this was not acceptable we needed to reconsider the relationship. No problems 18 yrs later ! One of the main considerations in buying our house was the possibility of expanding the garage to 4 cars.
My wife is very tolerant of the hobby cars I own. She knows its my mental health policy relative to problems at work. When I work in the garage I leave behind the crap from work and immerse myself in the work at hand.
As far as the 66 is concerned I let her test drive it before we bought it, she agreed to get it. She never crabs about anything - I think she'd rather me have a B body or an E body, but that isn't me - at least not now, especially with the prices those things are commanding -