Long piointed lugs, early '70s, color; it appears that it is.
det. the ST / SP diam. ID & OD respectively will narrow it down some. even 531 can vary in the precise ID in the ST, bear in mind, we're talking in .02 mils. here.

BESIDES.. google "free spirit bicycles with 531 tubing.".. a rental place rents THAT bike.
click-on the second listing. I can't be bothered with intricate html s