If you want to have the experience of the 1960s/1970s today, buy a first class ticket. It's fairly comparable in price (inflation adjusted) to the 60s/70s main cabin and you get plenty of leg room, plenty of overhead storage, and at least on Delta and Air France, fairly decent food.

Right now, I can book BOS->SAN->BOS for $945 in first class. Granted, COVID is happening, but I've bought that ticket in the past, pre-COVID for that same $1000 +/- a small margin.