4160 is a model number indicating a non mechanical secondary Holley carburetor. Holley makes 4160s from 450 all the way to either 800 or 850 I believe. The list number is what narrows it down further.
I thought 4160 was the spreadbore family designation and 4150 were the square bore carbs, not individual model numbers. Think there are DP and vacuum secondary in both families.