M1 Single Plane Question

This sounds like a very well matched combo. Is the converter a 10"? What is the 60' time? What is the present et & mph? Is it hooked and leaving soft, or is it spinning the tires? Personally, if it was my car, I would work with the 950, as I think it could possibly pay a small performance dividend over the 750 on this combo, but its close. This is just a guess, but I think if you run the 750, it will probably like a 2" open spacer, the 950 will probably like no spacer, or the Wilson super sucker. The cam is what I would honestly consider to be on the small side, but it sounds like its very well matched to the compression ratio you are running. I usually shoot for 190-200 psi cranking compression but I probably have better pump gas than you do. We have Chevron 94 up here, its pretty good. Whats the lobe separation, 110? Just a guess. Measured compression ratio is around 10/1?
Whatever carb you use, I'm thinking this combo is going to like a fairly large shooter, as the converter sounds fairly tight, and the intake has a failr amount of plenum area. If both carbs have dogleg boosters, I would figure you are probably gonna end up somewhere around a 40 on the primary side, and a 42 on the secondary, but this is just a guess, and the best way to go is use the method I suggested earlier. Annular discharge boosters will be ok with slightly less shooter, as they are more responsive.
I always prefer to have people understand what they are doing rather than just try to tell them what will work.
Basically, when you whack the throttle-plates open on the starting line, there is a bog, or lean spot, until the vaccum in the venturi gets strong enough to start pulling fuel through the main jets. The booster venturi is a smaller venturi within the main venturi that helps to amplify the vaccum & start the fuel flowing through the main jets sooner, but there is still a considerable lag between the time the throttle plates whack open, and the time fuel actually starts being pulled through the main jets. The job of the accelerator pump is to add extra fuel into the system until fuel starts pulling through the main jets. It really helps to think about the process in these terms. If the pump shot is not instantaneous, or does not deliver enough fuel quickly enough, the engine will bog due to a lack of fuel. ANY throttle movement should result in fuel coming out of the shooters.
Hope this helps. of course there is FAR more to carb tuning than main jets & pump shooters, but working with these two will get the car pretty close at the track. Now if you REALLY wanna open a can of worms, try to optimize WOT, and part throttle cruise at the same time, but I'll stop here for now.