BEST advice is do your own measurements on YOUR car.
Rumor is the 64 tapered axle rear is wider than the 62/63 or 65.
Most say that 8 or 8.5 wide rim works well with 4.5" backspace.
I have a 62, with (I think) a 65 housing and axles. I've got a 10.5x28 slick on mine, with a wheel with 4 7/8 b.s., but I use a .300 spacer(essentially becomes 4.5") to center it up, and get the tire away from the spring. I've also got a 10x28 slick on a 4 3/4 b.s. that fits good.
Your 15x7 will work great with somewhere around 4" b.s.
( I don't do that offset crap. Offset has to be calculated, then you have to figure out which direction is plus which is minus. Backspace can be measured, with or without a tire on the rim.)