Just processed a roll of found exposed Ektachrome 64, there's images on it, but the base fogging is quite high so they're only just visible.
For minimal fuss I would get it pulled processed 1/3 to 1/2 a stop to get a little bit of extra density back, since it wont be projection quality anyway.
Processing as a negative will get you more of an image in the case of really bad base fogging.
If you want to be creative you can rehal E-6 process and re-process in colour dev to keep building up dMax/density, you have to pull it out before it reaches colour dev, and use a dichromate/sulphuric acid b&w reversal type bleach, wash out the bleach and sulphite clear etc, then colour develop, then wash that out, use a rehal type bleach, wash/sulphite clear and re-colour develop and so on.