Factory part numbered Small bolt ralleys are all 14 x 5.5 . Aftermarket Small bolt ralleys can be had in sizes from 14 x 7 all the way to 15 x 10.
A number of years ago I even had a pair of 15 x 6.5 Small bolt ralleys made , because I don't like the way 15 x 7 Small bolt ralleys look on the front of an A-body.
And no , they never made a Small bolt Magnum 500 wheel , I seem to get asked that a lot. That would have taken some major re-engineering , wow !!

Frank