It has been said for many years that Atlas mags only were made in 14x6 and 15x6

I don't know if any other size has been found.

Do you know if those 15x6 Atlas wheels would clear 4 piston calipers Joe? My TTOs do clear them without spacers. The wheels that I had on my 69 Yenko would not clear 4 piston calipers. They appeared to be identical to Atlas wheels, but no manufacturers name or logo anywhere.

Pic

This was Don's 68 demo car and was not a COPO 9737 so I'm not 100 per cent sure it had disk brakes but most likely did.

Wheels are hard to ID because they copied each other.

Some wheels can tell more from a photo of the back side

They do look like 15”