The way I shoot out-of-date Ektachrome (4x5 in my case) is to shoot one sheet at box speed with normal development and assess the results. Then introduce compensation, as indicated. I'd do the same in other formats even if I only has one roll with which to experiment. Tehre are too many variables involved to really support guesswork.
it is 35mm, from 2003, stored at room temp. I have 18 rolls. Also a few rolls from 1980's and 1970s. I want to develop them as a normal color positive film, for projection on the wall or scanning.
The way I shoot out-of-date Ektachrome (4x5 in my case) is to shoot one sheet at box speed with normal development and assess the results. Then introduce compensation, as indicated. I'd do the same in other formats even if I only has one roll with which to experiment. Tehre are too many variables involved to really support guesswork.
I am thinking of cutting a short snip test-piece and sliding in the back of my Leica iiif, exposing at box speed, developing, then compensating on the next piece. I've done this with other film and the old Leica model makes it easy. Avoids wasting entire roll for a test. But need some initial guidance for development, especially the old film.
Develop your test(s) normally.
E6 process was introduced in 1976. When you locate the 1970s film, be sure to check that it wasn't designed for the older processes, such as E4.
My experience has been very poor with outdated EPP (Ektachrome 100 Plus).
I have had good experience with outdated EN (Ektachrome 100) and Ektachrome 64 that had been frozen.
If your tests show poor results in E6 process, they might cross-process well in C-41...with resulting higher contrast and artsy color shifts.