Holley 3310-2 2946 4bbl
I may be wrong, but the 3310's I remember from years ago (very early '70s) were 780cfm vacuum-secondary carbs with metering blocks on both sides.
Your pics show a vacuum-secondary carb with one metering block and one metering plate.
Someone correct me if I'm remembering wrong. Holley has probably changed the configuration or added optional numbers several times over the years.
