Okay, got to it this morning. (All following are 5 on 4.5)
15x7 polished TT2 VN501 (Old style, 501 is now a different wheel, if I remember right) 3 3/4 bs
16x8 polished TT2 VN515 4 7/8 bs (with a 10x16 slick, fits beautifully on my 62 savoy)
Following are all 70s vintage wheels, with typical problems of the time:
15x7 200s daisy (ARE) 3 7/8 bs. Fits virtually anywhere with as much tire as you can put on a 7" rim.
15x8.5 200s daisy, and 15x8.5 Ansen prostock (straight spoke original tt lookalike), both with 3 1/2 backspace.
The vintage 8 1/2s are virtually worthless, unless you have a car with a full open wheelwell. They are so close to the fender, that a proper width tire for the rim width will rub, IF it can even be bolted on. So the choice is: way too small a tire, or set on a shelf. They are sitting on a shelf.
For reference, the offset for the 15x7 tt2 is 6.3mm, the offset for the 16x8 is 9.5mm
Plus or minus, I don't know, or care.