[jmarkaudio]

You need to figure out how to generate more idle vacuum so you can close the throttle blades up. The t-slots need to be covered or you will have a tough time getting it to idle without closing the mixture screws all the way, and even then it won't be enough. More initial timing might help, if you run a distributor with a vacuum advance using the vacuum to add timing under no load can help. If you find that you have all the timing it will stand, I would look at advancing the cam.

As a last resort, make the idle feed restriction smaller, drop it to the point where it's tolerable at idle and doesn't cause a stumble coming up on the throttle. Being a race car you should be able to find the happy medium. You can try to solder the restriction after measuring it, it's the small tube in the middle of the larger one in the booster cluster. You might want to get a spare to play with to do this. The other place looking at what I can find is there may be an idle down channel restriction, making this smaller
will help as well. Again these are last resorts, making more idle vacuum to allow the blades to close is your best bet. Here is a picture to give you an idea on what is going on.