Thanks T-Mar. Appreciate it! Browsing through here - seems you have a quite a lots of answers I have about these old bikes.
One more for now: assuming these are freewheel hubs and not cassette hubs?
If so, could I move to a 7-speed 34t freewheel and use drop bar shifters? If that's where I wanted to go - would I start getting to the world of spreading the rear chainstays for a newer wheel setup to accommodate that - or would it be a straight swap and just a matter of indexing with a hypotethetical new 7-speed shifter?
Love these frames and the story... but maybe need to realize what I am potentially getting into in terms of tinkering, swapping, adapting. I like fooling around with this type of thing but have only done it with 00's and newer machines. New territory.