I finally got the thing running! The issue was certainly from a lack of experience. My carb has clearly been rebuilt before (Im pushing 270k miles and the rivets on the idle fixture had been drilled out). Apparently the last person to rebuild this carb heli-coiled the air / fuel mixture bore so it puts resistance on the screw and keeps it from backing out without the cap. I was "backing out 2.5 turns after you start to feel resistance from the pin seating" not from it seating at the end of the hole, but from it engaging the start of the heli-coil. Is this sort of fix common for our carbs, or did I just buy a jimmy rigged car? Its good to go now - thank you all for the help.
