I believe that PAA 707 scheduled service ended around 1979. A few PA 707's were leased out to other airlines into the early '80's. AA ended their 707 service around 1981 and TWA flew them until Oct. 1983.
Looks like their 707 service from JFK to Europe ended in 1977-78, but the nonstops to Dakar and maybe Monrovia lasted into 1979. The 2/80 timetable still shows unspecified narrowbodies from JFK to Trinidad and Caracas--I guess that means 707s? They disappeared later that year.