I seriously doubt this is 1970s. The New Shimano 600EX group is 1984-1987 and almost certainly 1984-1985, based on the friction levers. The tubeset is mid-range and at this level the frame characteristics are more typical of mid-1980s. The group is age and level appropriate for the frame.

I don't think the top tube damage is due to a crash. More likely, as previously suggested, it's a wear mark from a strap, based on the pattern, bare lug tip and lack of similar damage on the down tube.