I have a 1975 Peugeot TSA. After advice from here, I ditched the gurtner carb and out on a dellorto sha 15.15. It came with a stock 68 jet but didn’t run well. I ordered a range of 70’s. I started with the highest which I think was 76 and ran it on the highway for a couple of miles and this is what my spark plug looks like. I’m guessing I’m still lean and need to get an ever higher range of jet sizes next? First time doing this so appreciate any insight. Thanks!!