So you want 300-400whp and little lag. You should look into the ball bearing turbos or the Go-Autoworks Spec Bullseye .55 turbo. I've seen this turbo produce some impressive results.
You may as well just get ID1000's for your injectors. A search and you'll find injector horsepower calculators.
In terms of piston and rods, there's the custom length rods paired with Vitara pistons that would be cheap. However, a few people have been having issues with Vitaras recently. If money is not an issue, get Eagle rods and whatever Wiseco pistons that put your compression ratio in the 9-10:1 range.
The camshaft, search. I know there's a thread updated yesterday about what cam to use of 600+ whp and I know there are many threads about cams for any particular power goal.
I hate to be the one to tell you to search, but everything I told you could have been found very easily. However, I'm happy to help out a fellow member get on the right track.