Ctein has a review of the new Fujicolor 160S and 160C emulsions in the latest PhotoTechniques. He says they are "approaching the fine-grained league of the now-legendary Kodak Ektar 25". Not bad, and 160 ISO thrown in. Probably worth running a roll or two for yourself.

I forget how long ago Royal Gold/Ektar 25 was discontinued, many years IIRC. You might get lucky and find some, but I suspect you'll have a hard time finding a significant stash.