Does anybody know what color the foal would be? I mean obviously there's no for sure way of knowing, but has anyone else bred a paint to a blue roan? And if so do you have pictures of the baby? Posted via Mobile Device
So you have a red based overo and a black based roan, you could end up with a chestnut, bay(if the chestnut carries it), or black, with the overo gene present in the mare (you didn't specify), the roan gene, both, or neither.
I'll assume that by "overo" you mean Frame. If you don't know any of the genetic details about either horse than you have a pretty much equal chance of getting a solid (black, blue roan, bay, bay roan, brown, brown roan, chestnut, chestnut roan) or frame (aforementioned colors) foal.