I think its especially important to correctly identify - where possible - the factory part number on the strut tubes, as spring seat position moved around according to original fitment. Also important to ascertain whether the lower spring seat has been moved up or down at some point in the strut's life.
There were many small rolling changes to struts as production went on. For example, looking at the factory parts manual which covers UK market models you can observe no less than NINE iterations for RH Front strut assemblies up to October 1973 (E4215, E4126, E4127, N3425, N3725, E8125, E8126, N3525 & N4025). From '74 up there were many more...
With cars that are at least 45 years old at their youngest, pretty much anything could have happened to them over that time. In my experience, people often used to source used struts and then modify them to swap out with the originals. Some specialists in the UK used to offer suspension struts on an exchange basis, so if a car has been modified at all it is very likely that the struts on each corner are not the originals. That can make it difficult to put it back to 'stock'.