Kodacolor is a color negative film. It's processed C-22, which has to be made in batches as this chemistry hasn't been produced in decades. This is only available at a handful of labs. If this is indeed the film you are dealing with and you can't source the chemical components and run c-22 yourself, expect to spend 30-40 dollars a roll having a lab do it with a turn around time of 1-6 months. But I now have some doubts that this is the film you're dealing with. The film base is very dark black with a nearly purple reflection. I dropped some of this in regular Kodak fixer to see if it reacted like your film. It turned dark pinkish tan and the black film base turned perfectly clear, but this was only discernable after wiping the softened emulsion off with a rag. I didn't try putting it into a developer first. Those results sound somewhat different than the results you described, so it may be another film stock from that era.