Maybe to help - I never could establish whether the Cooey 60 was drilled and tapped at factory or by owner - I believe when Winchester Western bought out Cooey and sold the Model 600, that they were drilled and tapped at factory - #10-40 I believe.
Side mount uses four screws - there used to be Weaver base units that would fit that screw hole pattern - the base units here are simply marked as "1" - a straight small flat thing, and "3" which has an "over top" angle to it. Both base units used a long or short ring combo that attached to those bases with thumb screws - same ring units for either base unit. I know they screw directly on in place of the stamped sheet metal types that the old school rimfire scopes often used. Not sure that either the 60, the 39 or the 600 ever had dovetails milled - but easy enough to do, I think.