You need to buy the block, get it sleeved and blueprinted. I would try and find someone that you can talk to who does blueprinting, tell them what your interested in building and that you'll order all the parts yourself.
Blueprinting an engine makes it last longer and develops more TQ and HP. It balances the engine essentially.
JE makes great rods and pistons. Theres so much high end shit your going to need to order I'm not going to make a list of it. Theres probably a FAQ already on this forum of the parts list needed for exactly what your building.
450 seems possible, but to get above that on a 4cyln your going to have need really high boost, which requires more exhaust gas, which means your rev range better be able to crank out past 7k. I'm not saying you can only make that much HP with uber high revving engines but thats the nature of a turbocharger. Also things just don't hold together well going that fast so you can break your really expensive engine.
Your asking questions you can get answered by reading information that is readily available on this website and many other sites on the web. Most guys here don't like posting information thats readily available on the net that takes minimal searching.
Anyway you look at it YOU are going to have to go do research and get off your ass to get what you want. Go talk to some local mechanics, I'm sure they can help shed some light your way. Many guys around here that work on cars build their own or know people who do it professionally. I would start with them if I were serious about building an engine and NOT on a Honda forum( no offense to the knowledgeable guys out there! you know who you are!
). Some dork could get on here and give you shitty advice, if a mechanic gave you shitty advice his shop wouldn't be open for very long.
Places to go to talk to some people:
Body shops, Local mechanics, Managers of autoparts stores - the longer they've been into the auto profession the better the chances of them knowing where to go. If you've read for more than 5 hours about engines, as soon as you talk to someone you will know if listening to them is worth your time.
Good luck.