Mercury 302 used a little Holley. 1.563 throttle bores, 1.250 primary venturi, 1.313 secondary venturi. Like a "600 Holley" or a model 1850. The factory id was C8OF-D for stick, C8ZF-B for an automatic according to the NHRA tech info. The same engine in a Mustang used an Autolite/Motorcraft model 4300 carb.
http://www.nhra.net/tech_specs/engin...ts/FORD-68.rtf