Have you tried adjusting the idle mixture (2 screws under the fuel inlet)? If not, with the engine off run them all the way in to the stop (don't over do it), then back them out 2 1/2 turns each. Start the engine and warm it up, then connect a vacuum gauge and adjust the screws one at a time (slowly and not too much each attempt) until your get the maximum vacuum at idle. You may have to adjust the idle stop screw as well.
Also, do you have ported vacuum to the advance can, or is it direct manifold? I like to use direct manifold, runs a bit better that way.
Next disconnect the vacuum can and see what your initial timing is. Adjust to 17° to start with. Pontiacs like a lot of intial timing. Your total should come in somewhere in the mid 30's at about 2200 rpm with the vacuum connected.
As far as those jets, I think I have .069's in mine with a Qjet off of a '69 Buick 430.
