I have a 289 that came in a 63 Fairlane. the motor needs a rebuild. I want around 340 hp. can it be done with with factory heads. they have been ported, have screw in studs, and guides already. can I reach my goal with factory heads or am i better off just building a mild 302. I am tryin to keep to a budget of 1000 or less. any help would be great!