Brian Gardner from Australia has made ABC piston/cyl. sets for the OS .35S, and they come with a much improved conrod. Well received by users, too.
You might get lucky and find a NIP rod for the ST .35 from eBay or by advertising here in the Classifieds. One problem is that a lot of those OS .35S engines got ST .35C rods put into them...they fit, or can be made to fit. I forget which. Randy would know, and I'd sure recommend giving him a bell.
Steve