+1 on the dating, c. 1980. Looks like it could be a 1979/80 Super--with the old style bb, over-the-BB cable routing, engraved/concave seat stays and the beefy round spacer between the rear stays... -definitely worth the price.
+1 on setting the dropout cold--if it moves out of plane, use 2 plates and clamps. Might be worth checking alignment at your LBS when you are done.
Cheers