If you have the idle speed screw in that far then the carb is idling the main circuit (blades open past the transition slots). You either need to get a bigger carb (bigger throttle blades) or you need to drill some holes in the front throttle blades to let air in without opening up the throttle blades past the transition slots. A 0.100" hole in each front blade should do it.
Also a 268 cam should have about 15 to 20 degree initial ignition timing.
Try using paragraphs next time. Your post is very hard to read.