Means we have no dyno numbers, Wallace online says the 5.9 is at 341 horsepower. So the real question is this: What would it take to get the RV 440 over 341 HP??
With a 5.9l and similar cam Richard Holdener got 350-365 hp depending on intake he used, which sounds like your in the same ballpark, IQ52 got 387hp with 850, M1, headers and a 509 cam.