Thanks for the replies, everyone.

I didn't really put too much effort into getting the texture on the face to match up, mostly because I couldn't figure out a way that worked well. I think I did a decent job blending the beards together but the texture for the head was beyond me, really.

How would I go about doing that? I was thinking maybe copying a section of the painting and messing with blending modes and such but I'm not entirely sure.