It appears that the Aristocrat rib was milled for scope rings. Aristocrat makes a scope mount that replaces the rib if you want. I think it may take Ruger rings judging by the slots in the top of the rib, but I am just guessing. Someone will recognize the cuts in the rib and know for sure. Aristocrat is at
Aristocrat Products - Competition Proven Products They are very nice folks. The front adjusting rib on your gun is out of production now, you will want to hang on to it. I have never seen a .44 magnum done up as a PPC gun before. It probably makes it very pleasant to shoot.
Dwight