I grew up with '50s and '60s cars. There were many engines which burned less than a quart per 3000 miles and quite a few burned less than a quart per 6000 miles. In general oil was changed more frequently then so minor amount of oil consumption could go unnoticed. I also think there was a bigger percentage of high consumption engines then-production tolerances (produced out of range), or materials such as valve guide seals.
I have very good memories of the time. A worn smoky engine would burn quart less than a couple hundred miles, there were stable engines that would burn a quart per thousand (considered relatively high), a quart per 2,000 would be bottom of the average engine range, and there were quite a few which would only be half quart low at 3,000 or 4,000 miles. This would be for standard USA built iron block vehicles. Some high performance cars or high performance driving burned more than average oil.
Certainly many of these old engines rebuilt today will exhibit low oil consumption along the lines of modern engines. I also think the old engines would exhibit much better life if equipped with fuel injection, used modern fuels and lubricants. Bore wash from maladjusted auto chokes wore out a lot of the old engines prematurely. One thing in favor of the newer engines is they are lighter and warm up faster.