[68Stepbed]

I'm not familiar with the Summit carbs, but I'll help the best I can.

A few questions and suggestions first.
1: Your timing seems kind of low. My cam is slightly more aggressive, but most carbed applications I've seen use more timing. I had my timing set a 38* all in by 1200 rpm and held flat all the way past the rev limit. Is there any particular reason to back the timing back off after 4400rpm?

2: What's your thermostat temperature, and what's the typical operating coolant temp?

3: Vacuum or mechanical secondaries?

4: As geezer mentioned, power valve and idle vacuum numbers are important.

We can move forward once we have this info.