Looks like a Gevarm E-1, made in France, sold here in 1963 by Stoeger, other US and Canadian importers in the late 60s. Looks like a Euro version, isn't the muzzle threaded for a silencer? Yup, pretty sure that little 3/4" scope is on backwards.
Most Gevarms fire from an open bolt so a full auto conversion would probably not be hard. I trust you have all the required paperwork for that.
Are you SURE the magazine capacity is 60? They listed a 20 round magazine and the one illustrated is not as long as the 30 round mag of an M16 Achisson conversion I have shot.