I have a ‘54 AD into which I have put the rear from a ‘67 Biscayne. The Biscayne had 14x7” wheels with a 4” offset (backspace??) I would like to find a comparable wheel but in a 15” size. Any suggestions?

I also have seen a cross-reference chart for Chevy wheels but the offset is listed as L, M or H. What’s up with that?

Thanks!