Anyone know what film this is?

I bought some stuff and there are about 20 4x5 holders loaded with this. I think it maybe Ektacolor type-s but I can't find any info on it. The holders still have the unexposed dark slide position and there is film in at least one of the holders. It could be decades old but I thought I might shoot a few but what process would the developing be? I have never developed color before but I have a C-41 kit on the way and thought I would try it. I also have some Portra 160 in holders I shot about 10 years ago so how should I develop that?

According to this site, it is Ektacolor Type S as you suspected: https://www.photomemorabilia.co.uk/Colour_Darkroom/Early_Kodak_CameraFilm.html#anchor40

Ektacolor S appears to be a C22 film.

I don't believe C41 will work. You can develop it in B&W, or you can see if any of the C22 labs are able to process 4x5.

If you try to develop a C22 film in C41 at normal temperature, 38C, it will melt the emulsion.
There are some people that develop it in C41 at 20C and get results. AFAIK it was like a stand development.
I can't find the details for C22 but I did find some for Agfa CNS in C41. I know CNS was a different process to C22 but both originally had developing temperatures of 20C.
C22 and CNS are both obsolete processes.
http://www.florisdox.com/expired-agfacolor-cns-c41/
Let us know how you get on.

I've seen reports of usable results (at least for scanning) processing C-22 film in C-41 chemistry at 75F. You would need to extend development time, and use a formalin-based stabilizer (to complete conversion of the dyes), but the scans I saw looked good. You might actually improve this a little using the newly offered Cinestill ECN-2 kit, which has the correct developing agent (CD-3 vs. CD-4) for C-22 films.