I heard that the only difference between an 427 and 454 is the crank shaft. I was considering borring the 396 out and making a 454 or a 427. the main thing i was wondering was about the heads. The 396 has the stock heads and i was wondering if i could use them and if not what are some afordable ones. I would like to try to keep this under 3 grand if it is at all possible