I have high water pressure and my late sixties SQ easily overfills by two increments, even with hot water. So I have to be careful how I set it. The rinse agitation begins just when the water level reaches the top and begins overflowing, if set on cold. Warm always creates an overflow situation, and I don't mind.
The 1980 SQ has the larger solid-tub. Even if set to a warm rinse it never gets full before agitation begins, so it kind of shortens the true overflow rinsing effect accordingly. Probably Government intervention or pressure from the stupid Consumers Report. The Rinse fill needs needs a couple more increments.
The timed-fill Maytags were interesting. Depending on water pressure you got a little too much or a little less. However, I don't think they were any more prone to overflowing than any other perf-tub machine in those days. All you needed was a bad water valve.