I have always been partial to the Holley 600 vacuum secondary, List 1850 for stock 390s. I agree with 85lebaront2, the 428CJ carb at 735CFM is a outstanding choice for a warmed up 390, Ford also recommended it in their Muscle Parts Book builds. The 735 is a 750CFM carb with flared booster venturis in the primaries that really help throttle response on the low end. When I went to a 406 Tri-power set up on my 428CJ, the 735 went on to the 390 in the family car/bracket car. The change was good for almost a 10th of a second change in ET.

 

Josh, looks like the updated version of the old R-1850. The improvements will make it more reliable. It would definately be a good choice. I was just commenting I have seen "French" ambulances, and had to install a modulator on one at our scout camp during a camporee one weekend. It burned 7 quarts of Dexron in a 60 mile trip. FWIW, I used to own a carburetor and tune-up shop here in Newport News, VA. I sold many a Holley 735 for many different applications.

 

The trouble with those prettied up carbs is they don't stay that way and and a total bitch to get clean, other than removal, teardown and soak. Give me the old utilitarian carbs everyday.