Never knew there was a difference in the old and new style 390's, when I had the 2.0 in my car I got the carb from Summit, they still have it listed for $350.00, they also have the HP series 390 that is a race carb, ($700.00)
Anyways, my car ran great with the "new style" carb on a Weiend intake.
When I put the V8 in my car, I got the carb from an e-bay store called Extreme Performance Carburetors. You fill out a very detailed spec sheet on your car and they build and dyno test a carb for your set-up. I bolted mine on and didn't have to turn a screw on it, not even the idle! Very reasonable price to boot.