I’d be a bit careful jumping straight to dual double-pumpers. In a jet boat you’re usually under steady load, not snapping the throttle like a drag car, so vacuum secondaries can actually work fine if they’re healthy. Your old 1850s leaking is more of a rebuild/condition issue than a design flaw. Double pumpers with center-hung floats give better fuel control and response, but they
reef-spins3.com can be easy to overfuel if not tuned right. Cylinder wash only happens if it’s way rich. I’d say either rebuild what you have or go DP but keep jetting conservative and tune from there.