First off, I'm assuming you're talking about the pointy shaped mirrors. Not the tear drop Regal style.
I'm pretty sure they do line up. My father has an 86 SS and we just took the mirror out so the door could be painted. While it was out, I was looking at the 'bolt pattern' and it appears to be the same as Regals. There was a turbo Regal for sale, not too long back that had these mirrors. Was on ebay.