I bought a 1981 sunkisst stripped out with a berkley pump, witha droop snoot an A impeller. Put it together, dropped 396 dome pistons, big cam single plain intake, and a holley dominater 750. Boat runs good but it will pull 5000rpm at quarter throttle and 5400 at full throttle. My uncle had this boat when i was a kid. He had a small block 400 in it, nothing major down to it. He said it would pull out 6400. I dont remember as I was too young. Shouldn't a 396 pull it easier than a 400?