Maybe the 7sZ finders are best because the cameras are simply less old?? One need to take it apart and look for it! And, please, Jim, post the pictures, or send it to me to publish it.
IMHO it is very hard to evaluate cameras 40+ years old from a 1-1-usage basis. Maybe you have one example which aged in grace where the other didn't.
Dechert said also things about the finder of the P, V/L and VI, and aging of each model. From my personal experience with my personal cameras (just one each model; each with no haze in finder, excellent to good condition) I cannot follow him. Not at all. Maybe the finders of my cameras are not the same as they were new. Maybe of a specific model, or all of them, no example exists in the world which finder is as it left the factory... so comparing them on this basis is maybe impossible?
If any user will buy *one* camera, he will not buy dozens to create a statistic, he will buy *one*. In this case general advices like that (except "hard facts" which frames occuring, parallax corrected or not, small viewing field or wide...alike that) are of no big help.
Collectors or book-authors try to search for differences where no big differences exists in real-world usage. As a user, I would say all Canon RFs starting with the V, are great, except they are hazy, in general. Then, there is a development from the V to the P/VII: eye pupills and view of field becoming larger, frames appearing with the VI, becoming parallax-corrected and reflected with the VII... and all are eyeglass-scratchers except the P (but on the other hand, with thick glasses you will not see the 35mm framelines with it). So which to choice? I don't know. Best: all of them...