average,

Your mention of the cylinder indicates that you know about the change of transfer port size around 1980 (sure someone else can give a precise date) when the piston seal changed from leather to synthetic. Just thought I'd mention it here for the benefits of anyone else reading this thread with a similar query.

As Danny's pic shows, there have also been changes in the iron sights. I do not know if all the rear sights interchange. Clearly the fronts don't, going from an early dovetailed blade to a (1960s onward?) slide-on hooded unit with interchangeable elements.

And it also shows how elegant the early ones were. Myself, I think the 60s and early 70s ones usually have the nicest blend of features, looks, and build/finish quality. And I don't even really like 35s.