Twins in a 29 V is good especially if the boat is 8000 lbs+. On a cat you could accomplish the same with a single application with more horsepower.
With twins on V with stock 454's you burn a minimum of 25+ gals. per hour cruising at just 50 miles per hour. If you do your own maintenance twins are a bitch especially a boat that small - no space. Double everything, from impellers, to filters and oil.