I had thought about the Peden site. There are a lot of photos of his cave, steps etc. online but none of "the man" in the BRAC photo. The carving is certainly of a different tradition than the RA up river at Ballochmyle and the hairstyle has a certain "period" feel to it.
Postponed the trip this weekend due to sever weather, flooding and a heavy spate on the river. Will be down that way soon though.