John, its hard to say how old claw mount parts are because they dont realy change in the last 100 years. I dont now if you or your gunmaker have the skill's to make a claw mount but there is a new firm in the fatherland making claw mount parts being 100% exchangeable and ready.
http://www.zp-einhakmontage.de/front_content.php?idcat=5

claw mounts are an art of itself. I would recommand you to take this new made parts. there is not realy a difference to old parts!