Carb queery's

OK, backround info;

'73 Duster with /6 to 318 swap done with the regular bolt on goodies and a Crane cam installed. (Advertised @ 272/284 - .454/.480- 112 C-line.)
904 and Orange box ignition, MP distrib.

1st carb up was a small early AVS. Problem, will not idle. It can run on the main metering circuit, but not the idle. I could get it down to about 1,00 - 900 rpm's, but that's not the point. Swap it out for a

2nd carb, on the shelf I have a known 750 Carter AFB. A newer model purchased new by me about 5 years ago. I pop this baby on and it idles fine. However, no main circuit. Once I crack the throttle and the pump shot gets used up, it will stall.

I'm trying another AVS later. It is an OE part and it is the large ones offered.

Any ideas on wh the 2 carbs above are a problem. Now to add to the mix, yesterday when I tried to find out what was going on, I hooked up a vacuum gauge to the motor and found zero. I'm going to hook it up again to the manifol for a retry for a more accurate reading. The carb was the source of the intial reading. Timed stock to '79 specs for a base to start with since it is a '79 engine. It seemed like a place to start. and then go from there. Inital was 10+ ATDC/advanced.