By far...the most effective new replacement carburetor for a 304 or 392 with a 2v manifold is a Holley 2300, list 0-7448. Those are available only in a manual choke version, if an electric choke is desired, an electric choke kit May be installed as an additional component.
Do a search here in this sub-forum using keyword: "2300" and you will be buried in information.