Upgrading to 15' wheel vintiques series 63

15x8 with a 4.5” will be tight even with the 8 3/4 and SBP. It’ll depend on your tire choice, but you might need a spacer to make those work.
Will 15x7 with either 4 or 4.5” Bs work?

I could got 15x6 up front with 4” Bs and 15x7 with 4.5” in the back.