|These panels are no longer in continuity. Best forget reading them!|
Before "Marvel Time" completely took hold--throughout much of the 70s--Marvel characters stayed somewhat topical. This is best exemplified by Claremont's run on the X-Men. Magneto's past is tied to Auschwitz and the Holocaust. We are told Ororo "Storm" Munroe was born in 1951 and that was orphaned by the Suez Crisis. Jean Grey's tombstone gives the extent of her life as "1956-1980."
This can't be the Jean Grey that first appeared (likely as a high school sophomore) in 1963, though. (In fact, it doesn't seem likely that it's the same Jean Grey in that talked about meeting the Sentinels in '1969' in X-Men #98--don't know what Claremont was doing there.) Like the Golden Age Superman slowing melding into the a Silver Age one, the Silver Age Jean Grey slowly became the Bronze Age one while nobody was really paying attention.
A lot of people might not agree, but I kind of wish the DC approach had been stuck with by both companies. Instead of squishing and distorting things to fit a sliding time with very little to link it to real history, why not just switch the particular version of the characters you're chronicling every decade or so? The Silver Age Reed and Ben that fought in World War II would eventually become the Bronze Age Ben and Reed that fought in Korea or Vietnam, and the Modern Age ones that weren't in any war, You can keep the things they wanted and reboot others for each era.