GTX backspace?

I found good 8" wide rims with 4" backspace to mount Mickey Thompson bias L60 14's ( old school look) but wondering if backspace is enough for 68 GTX?

Those should work fine. I had some Crager SS's which have 4" backspace on the back of my 69 RR. Just swapped them out for some Mag 500's which come standard with a 4.5" bs. Both work fine with 275/60/15's, which I think are just a tad smaller than the old L60's.