I have there billet metering blocks on my 600s but couldn't get the cruise a/f ratio right. And jetted down to 57s (600) too lean. Jetting up on the 450s now.the front carb has 55s the rear carb 56s.
Are all three of those emulsion holes open on this block? If so, you should have blocked the middle hole off to lean it out some, and if that wasn’t enough you could have blocked off the middle and bottom holes. That would have leaned it out.
