Holley does make a marine version of the 4412, Holley #0-80402-1, however, to utilize the flow capacity of it(500 cfm), your engine would need to be turning 12,000 rpm. Even its little brother 300 cfm, 0-80320-1, is way too big. The Rochester is a good carb, not difficult to understand. HP Books used to have a very good book on Rochester carbs.