SBP 70 Dart With 15 Inch Cragar Backspace Questions

Have a 1970 Dart with SBP wheels and completely stock. I have been reading for days to come up with the right combination of wheel and tire.

Let me preface this by saying I would like to keep my SBP if possible. I also eventually plan on converting my front drum brakes to disc.

From what I can tell this combo will work.

Front: 15x6 with 215/60
Back: 15x7 with 235/60

With a Rallye wheel, that would give me a 4" backspace on the front, and a 4.25" backspace on the back. I also believe this wheel would have no problem with an SSBC disc conversion on the front.

The problem is, I would prefer Cragars with the same size tires, but the backspace is less than the Rallyes and I am not sure if the same combo will fit, or will accept the SSBC brakes.

The Cragar 15x6 only has a 3.375" backspace, and the 15x7 has a 4.125 backspace.

Any ideas?

Thanks!