buick 455 motor

hello, i'm new to this site and just wanted to say hey! i am looking for some info on a 455 buick motor i just bought, maybe i can gets some help. ok for starters this motor is not going to be put in a car. its going in a boat, the last three numbers on the block are 681. i think its a 71 or 72 year model. was rebuilt about 50 hrs ago. dont know what all they did and i dont know the hp. but anyway my question is how do i find out the hp and what do i have to do to get that motor to produce about 400 hp. i dont know what to do... sorry for the long post.

thanks for the help

Edelbrock performer aluminum heads matching cam and intake should do it.

thanks!

Check out www.v8buick.com (http://www.v8buick.com), there is a TON of info there on the 455, and several guys with them in boats.