That is cool. When you list it, I would be sure to put boyshorts, full legged and hot shorts in the description because they were selling modern bathing suits with that kinda bottom as "hotshorts" last year. Its not reallly a leg like a short, but is is not the triangular shape that is standard for a bikini.
I am only thinking late 60s - or very very early 70s at the latest because in my memory, the bra tops were not as structured and more string bikini-ish as you got really into the 70s. Even if they were more modest, they starting looking less structured and this is still looking more like the way a bra is structered like earlier suits. I could be totally wrong, too.