R3 process Ektachrome Paper - can it be fixed out and the substrate re-used?

I have friends who are happily going down the road of Carbon Printing. They have learned that fixed out RC black and white paper can be used as the substrate for carbon prints.

They have two unused/unexposed/undeveloped 500+ foot rolls of 8 inch R3 process Ektachrome paper, and were wondering if they could re-purpose it as substrate for carbon printing.

Any thoughts if this is possible? If so, how?

Anyone have any other use for the paper?

R3 paper is quite rare and interesting material, so I do not think that using these rolls for carbon prints is the best way. Perhaps you can find some people, who will be able to pay some money for it. On ebay, for example ...

I raise my hand of interest in that r3 paper...

I'll tell my friends about your interest.