My fault, I forgot to mention the article shows a Holley. It's the same concept tho. I can't see the transfer slots in your pics (they're in the bores of your crusty primary throttle blades). Check out post #10 from 454HO in this thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=435769. You can see the vertical transition slots at the tip of the throttle blades. They look rectangular in his pic and they need to be a square. You don't have to get them perfectly squared with a feeler gauge, your eyecrometer (haha) is enough. Your idle adjustment screw moves the throttle blades, as you noted, and that is how you square the transfer slots. Your fast idle screw doesn't affect the transfer slots, it's function is to set your choke rpm (1500 rpm stock) when warming up the engine.