Single strip 3-D/polarized light combination was used well before 1970; in fact, a few of the films in the 1950's wave were offered in various single strip methods, though few theaters bothered. The ship had sailed by that point.
Over/Under 35mm process was used in THE BUBBLE in 1966, which I believe was the first feature to get released in that format. This was more widely seen a decade later when it was re-issued as FANTASTIC INVASION OF PLANET EARTH. The over/under process was the method in which most 3-D movies were released in the 70's and 80's; though as Lee pointed out, a few were also screened in a side by side single strip format, most notably re-issues of HOUSE OF WAX and DIAL M FOR MURDER.
I can't say I'm too impressed with the idea of reviving over/under unless its tremendously improved; as the image was usually pretty grainy and dim. With careful attention it can look OK, but it usually didn't. Cameron's GHOSTS OF THE ABYSS had a few over/under 35mm playdates in 2003; and the screening I attented had the worst 3-D projection I've ever seen.