I would suspect the 14x7 backspacing would be similar to the 15x7 backspacing, which is usually 4.0" or 4.25". The factory station wagon wheels are 14x6.5. I put a set on my '67 Newport with P245/70x14 BFG Advantage TA whitewalls back in the earlier 1980s. With the jackstands under the rear of the rocker panels, the springs at full droop, it takes some wrestling to get the tire between the rear brake drums (NOT the 11x3" brakes!) and the quarter panel to get them installed. Once past that tight point, no problem. So be advised.
IF you are considering the Supreme wheels, all of the ones I've seen in catalogs have less backspacing than other wheels for the same rim width. Which means the wheels will be nearer to the outer sheetmetal as a result.
You will have far better luck with 15" rather than 14" sizes, in tires and wheels, from what I have seen. What about some VN501s in 15x7 4.0" backspacing?
Enjoy!
CBODY67