It seems like every couple of weeks this question comes up.
First let me say that your expectations of 400 to 450 hp out of a 327 are not practical, not naturally aspirated anyway. Making power is a function of moving air through the motor, the more air you move, the more power you make. The smaller the motor is, the higher you have to rev it to move the air through it. For instance, a 350 bored and stroked to 383 will move 665 cfm at 6,000 rpm's at 100% efficiency. To move the same amount of air through a 327, you'd have to rev it to just over 7,000 rpm's. Now, here's the kicker. In order to make power up to 7,000, you'll need more cam and more compression ratio than you would with the 383 and once you start that, you're moving away from a street motor and into the realm of a race motor. You see, any cam you install in the motor will have an operating range of about 3,500 rpm's. In other words, it will make power from 1,000 to 4,500 rpm's or 1,500 to 5,000 or 2,000 to 5,500 or 2,500 to 6,000 or 3,000 to 6,500 or 3,500 to 7,000 or 4,000 to 7,500, etc., etc. So you see, in order to make power to 7,000 or 7,500 like you'll need to do with a 327, you'll have to give up power in the lower rpm ranges where you need it to be a street motor. Now, if you are only going to race the car, then o.k., no problem. If you will drive it on the street, then you will need steep rear gears and a 5 or 6 speed trans or if running an auto, you'll need a very loose converter and that sometimes is a pain in the ass because the converter won't lock up and will build tremendous heat when driving around town, etc., etc.

I'll let you digest what I've said here and get back to me with any questions you may have before I continue. Yeah, I have a whole lot more to say depending on what you come up with.