It would be a fun bike to keep.
Not all 1000cc had the tag, but if it was a Cobra package it would. Lokk on the back of the head by the carbs, some were stamped R.C.. & maybe some blocks where the raised pad is that says 736cc.
The R.C cams ran big clearances, if you go to check the valves, check them first cold, if its a mystery cam, it can be hard to tell what they should be set at.
Is the frame cut under the tank?, common mod to access topend, some are sleeved back together, some left out completely..
I bought a 900cc one that shrunk to 836cc when I opened it up..