[3X24SPD]

Hi Dick,

I have a couple of those beautiful Kauffman TriPower Intakes on larger motors with higher compression & large roller cams, running Rochester Carbs.
No bucking issues.

Off the cuff, it sounds like yours might be going lean in the transition between the idle circuit and main pullover.

You didn't mention where you are at with ignition system (stock Pontiac points I assume, with a good coil), vacuum advance & timing- which could be contributory.
I might try a couple easy things and see how it responds:

Try opening the plug gaps up a tad- and see if it improves the situation.
A wider gap would light off a leaner mixture better- see what happens.
Depending on if/what you have for vacuum advance numbers, try disconnecting and plugging the vacuum advance and see what happens.
Something like what you have I would expect manifold vacuum in the 10" range at idle. Should have something like a B28 Vacuum Advance Can at minimum.
Static/Total Timing is another thing you could try playing with and observe the results.
I assume you have a proper ignition curve set up, and with that you should be pretty much all in by 2500. I would think you would be somewhere around 12-14 initial with around 34 total- with those iron heads and that high of compression. Try bumping the initial down 5 degrees and see what that does.