The jets have matching metering rods, not sure how piano wire would work.
But that brings up another option to lean things, fatter metering rods, prob won't effect WOT but would effect the rest of the time.
Just thought of another thing, is your carb a CAP carb? The jetting on those is different still. In 67 120-310s is standard with 120-297s being 2 steps lean ( might be a misprint cause 120-294 is called out to be 1 step lean)
