I have considered adding an under BB plastic guide, as GOD did incorporate later, but it seems I ought to keep Geraldine as GOD built her. Instead of drilling and screwing, perhaps I can figure out something less permanent.
Even if Gerry didn't know about Teflon housing liner you could use that, maybe. On my winter project 68 Grand Prix I used a bit of liner salvaged from a modern shift cable housing that was heading into the recycling. I have that under the DS cable guide for the RD cable. Works just fine and stays in place. One of those might snug into those BB slots and do nicely. Also keeps out the ground up quahog shells that the tires kick up from your New England roads.