Actually, I think the old Weavers are fine scopes, I even use a couple of the old "J" series 3/4" scopes with no problems. That mount, which is the ONLY mount for the 340, offers very little flexibility in scope position, it often is not possible to get proper eye relief with some scopes. It may be possible to cut down the side rail a bit but if the old Weaver is clear and the eye relief is OK I'd not worry about it.