It is hard to tell from the pics of your rifle, but that does not look like salt wood damage, rather it looks like damage from neglect.
* All salt wood is Claro walnut, your rifle's stock looks like European walnut.
* I do not have the date codes right here in front of me, but salt wood stocks were used from 1968 to 1970 on Medalist, Olympian, and some Safaris, basically the fancy firearms. Your rifle looks like a Browning Hi-Power rifle, the basic model with European walnut.
* Yes, the varnish finish is chipping and peeling, typical for Brownings of that time period that were exposed to moisture. Salt wood stocks were finished with a high-gloss polyurethane finish, and these finishes often peel off in very large pieces.
* The rust on the barrel, action, and scope also seem to indicate neglect.