This may be the place to ask. Or keep up the flea-bay searching.
I've got a few or maybe just two old/new sprockets around. I think they might be for a 350 twin, but similar enough to 350f if not the same, maybe they are adaptable to anything. They are NOS with no wear and no indication they have ever been installed. Not sure how many teeth, both [of the three ] are maybe originally meant for a twin 350.
Honestly i'm not sure what they are, I have at least two I can dig out and take pics of , and if you are patient, might take a week but I will dig and send pic if you PM me. They are here somewhere.
Other than that I might forget I ever posted this.