1966 Fury Wheel backspacing

[cdnfury]

I am looking at some 15 x 7 mags that have 3.5" backspacing would this backspacing be an issue on the rear ?

 

[rapidtrans]

Might push the tires out pretty close the the skirts.
Typical backspace for a 7” wide rim is 4.25”.

 

[cdnfury]

Thanks I thought it maybe a bit tight