Since the upper bearings with either dowels or tabs have the same outside diameter, it's a simple matter of using a narrow grinding stone on a Dremel tool to make notches in the block for the tabs to fit. Just be sure to get the slots positioned correctly- - - - -"Measure twice- - - -cut once"! Drop me a PM and I can probably walk you through the procedure with a phone call. You'll need to have the block stripped down completely to be able to do a good cleanup after grinding on it. I've also filed the notches into blocks, using a 1/8" square tool and die maker's needle file.
www.ebay.com/itm/177987239469?Jerry
