Well how thick are the hubs ? Just add that to the flange to flange !!!
Not exactly Vern,
many/most cars have different front and rear widths I believe. You are correct. According to the '69 FSM, the front is .3" wider than the rear. The "tread" is 59.5" compared to 59.2".
I do not know if "tread" is hub face to face or wheel centerline to centerline. As you see below, the FSM does not specify/explain.