Oil capacity/dipstick discrepancy between two 1962s.

Allot of things could have happened in the almost 60 old.
As simple as the original dip stick may have gone missing.Then replaced with one that was from a different vehicle.
Easy thing to do is drain the oil from each cars. You don't have to drain the filter.Per the factory service manual the pans(all) hold 4 quarts.Measure the oil if you are wanting to reuse or put 4 new quarts of oil in each car. Read the stick from one, then install the same stick in the other.See what it tells you.
Then do the same with the other stick and see the reading.The one that shows full with the known 4 quarts in the pan will be the right one.Remark the other stick to match.
Also remember if either engine has never been rebuilt (I have no way of knowing, this is hypothetical )old engines can build quite a bit of sludge that will decrease the pans capacity.
Just as a note the factory service manual (1962)recommends to change the oil every 2 months and not to exceed 4,000 miles. I'd bet a dollar to a donut that never happened.