Holley List 4440

Have you seen these? You can tell from the venturi size that it "appears" to be a 600. That's probably what it is.

R4440 Carburetor Info Page

Holley Carburetor Master List Page 30 - The Old Car Manual Project

1967-69 Chrysler w/383-440 V8 - Holley 4V Carburetor - List #4440, P/N 4-220 | eBay