some strange details: the Short (apparently Campy) DOs have the "portacatena" drilling, and the cable routing is above the BB, but not standard cable guides here, these look like one-offs. The juncture of the DO to the chainstay is very wide: is that just a choice not to grind the DO down to merge with the stay? or a very narrow stay? Anyway, some of those details (and including the single set of WB bosses) would point to a late '70s or early '80s frame, but there's the FD braze-on, sort of a later feature.