Hard to find…

I thought 4.25 was a pretty common BS.

Seems like I've measured that lots of times.
With cragars the most backspace I could find with our bolt pattern is 4.1. I have 4.1 right now. It's ok but another 1/2" would be better. When I read through this site most people were reccomending 4.5" BS as well. The calc I used said 4.5 too. I'll keep looking. Thank you