Drive chains are apparently stronger than they were in the 70's. I wonder if a newer cam chain would be a step up from original. What worries me more than anything about the cam chain is the rubber tensioner wheels. Didn't someone come up with a more solid setup a while back? If I were doing a cam chain update, I'd sure be looking into a better tensioner.
Whoops, sorry. Just reread that you're doing primary chain not cam chain. Ignore it all.
Yosh had (has?) a steel tensioner for racing apps, because the rubber would chunk out of the regular ones when held at 9k RPM steadily. Also, the oil flips out of the chain during the reverse-bend around the wheel, so there are some aftermarkets slipper tensioners (M3 Racing used to have them) like the Baby Four chain path has, for continuous hi-speed work.
Rumor has it that a fellow in Poland had some tough new material and is making some, too. It's been on a post, but I don't know where to find it at the moment.
