here is the back ground-recent purchase, rebuilt 1.7 with a kit and conversion to dual webbers all before i got it. it has new cam for the webbers, fuel tank cleaned, just got new fuel pump, fuel filter is fine. arizona car (altitude) now in Texas, i don't have all the carb settings or webber model numbers.

starts fine, going through the gears for town driving no real issues but when on highway starting at 3000-3400 rpms when in steady state there is a periodic fluctuation in the power of the car. if i put it in 5th gear and roll down the highway and keep it under 3000 rpms i don't get the slight transient missed beat, hiccup or what ever.
mechanic can't give me credible first approach so what does everyone out there think.

most likely carb adjustment needed?
coil, electronic ignition, cap, wires , plugs?
work back wards and check plugs, compression/leak and then look at carbs?

Start with the basics. Points, plugs, cap, rotor, wires, dwell, timing,valve adjustment, vacuum leaks, fuel pressure, compression. I would do all this first, since the car is new to you. Then I would know what I was starting with. For me carbs would be last, especially given the symptom of a steady state misfire.

When this same thing happened to me, I tinkered with the carbs/jets for a long time. Finally it was the new (123) distributor that fixed the problem

Distributor