hello there Chris, I'm Scott,
It kind of sounds like you don't have power going to the idle soleinoid. Have you checked power to the soleinoid at the base of the carb on the left side? These have a bad tendency of sticking also, check to see that it is clicking when you apply power. Let me know what ya find.
Please be sure you are 100% satisfied with my answer before you hit accept! Bonuses and postive feedback is much appreciated!
You have to get the timing right before you can adjust the carb. Normally I set the timing at about 7 degree's BTDC and it should run out at about 30 degree's BTDC. If you have points, which I'm assuming you do I'd start with them with. Make sure are in good shape and not pitted, if so replace them and the condensor. The point setting is 18 thousands, make sure you set the points before you set the timing. Once you have this all done, then adjust the carb. Here's a link that is very informative on adjusting your carb. Copy and paste it in your browser. Do make sure your accelerator pump is working well and the dump tube in the carb is not plugged.
I do appreciate the accept, but I wish I could have been of more help. For some reason my manual source is down, probably due to server probs. Anyways I found this great site, it goes into very good detail on your 72' A little boring, but it is informative. Ya know I was thinking, make sure you run something through the points. I've had some misfires and problem with new point that got a little dirt in them when I was gapping them and they don't get good contact. I run a piece of clean card board through them to make sure they are clean and contacting good. Check out this link. Gosh dang I hope this helps!