NEED some help....idle issues after cam swap...

I know everyone has there opinions on the 284/484 Purple Shaft cams, well my grandfather and I put one in my 71 Swinger with a 340 yesterday.....the 340 is out of a 68 GTS dart so it has really good compression and the "X" heads, it's bored 30 over as well and has long tubes on it. Well we got everything in started it up, it fired up instantly and sounded great. So after a little breaking in my Pap (who's done Mopars for over 40 years) went to set the timing so we could get the idle set....and now the problem, it won't idle. It has one of the edelbrock carbs that look like the original style carbs, well the air/fuel mixture screw on the drivers side does absolutely nothing....and the idle screw is so touchy! You barley turn it and the idle runs clear up to 1200, you barley move it the other direction and it falls and than shuts off. Any suggestions?....