"I do wonder how much such a machine might fetch on eBay, so it depends on if I need to finance any new 531 conversions, as Kurt mentioned "

531 is a dime a dozen next to this remarkable classic. Keep it. Seriously. You'd have to pry that one from my cold, dead, fingers, and even then I might come back a zombie and exact my revenge... that bike has serious mojo.

I've noted old Sports models have gone up in price on ebuy recently, but not to any ridiculous heights that mere poor folks like me can't afford. Locally, I just passed on a pair of early seventies ones myself yesterday, as I still have one in the basement to work on. They're not terrifically valuable (in a strictly monetary sense. As we know, money is fleeting and the true value of a bike is higher than any tawdry fisical number). Yours, however, is especially cool. I'm not sure what the value might be.