Your description of the problem is classic LATE- - -VERY LATE timing symptoms. Get the pointer and ball aligned in the window in the bellhousing with the engine stopped. Loosen the clamp screw on the distributor and rotate the housing clockwise until the points close. Turn it back CCW until they BARELY open. Tighten the screw down. This procedure sets static timing. The engine should start and run at a normal idle speed of 500-600 RPM as long as you have the basic carburetor adjustments close to correct. Lightly bottom the idle mixture screw by turning it clockwise, and back up about 1 1/2 turns for an initial setting. I would be very surprised if following the above procedure EXACTLY does not result in a good idle.
Jerry

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