What cam and how much vacuum? Engine vacuum works against the primary metering rod tree spring. You may need a lighter spring to even things out at low vacuum loads. What is your carb number? It should be stamped on the driver side rear bolt mounting flange, facing the firewall and start with either a 6 or an 8.

I tuned my thermoquad with the a/f meter and if memory serves I had the idle around 13:1, the 40mph cruise was around 14.5 and the 80mph would have been more like 15.5. I never got any ping by running a bit lean at high speed so I left it as-is.