Upgrading to 15' wheel vintiques series 63

Im doing a Kelsey Hayes swap on the front of my 67' Barracuda.

Im planing on runing the series 63 OE style wheels and going to 15" staggered width. My question is, their 15x7 rims seem to only go up to 4" back spacing, is that enough to work the the KH and what size tires will fit without issues?

In the back Im looking at 15x8 with either 4" or 4.5" back spacing, I think the 4.5 is a better option but not sure exactly what size tire I can run there either?

Cheers, and thanks in advance. Im in Canada so ordering and shipping is an ordeal, want to get it right.