Thanks for the answer!

this is a Panasonic found in Germany, and it is known that the german importer fitted the frames individually. hence i don't think the parts can give us much help. The setup with Zeus derailleur and Mafacs that are clearly pre-78 makes me think someone bought the frame to replace a broken one and had the parts moved over.

i do think that the work on the chainstays/dropout connection might be significant.