Whats your budget?
The motor can easily handle 300whp so your 250 -300 hp goal is easy. Since you did mention you want a tough motor, I would recomend a set of rods and pistons (eagle rods, and j/e, wiseco,etc for pistons), sleeves arn't necessary because you can easily make 450whp on stock sleeves. I don't know a whole lot about headwork so I'll leave that to someone else to answer.
Tuning...look into hondata for tuning....
A lot of the stuff that you inquiring about is stuff that you should research on your own...
Why are you planning to build the motor to 200hp N/A then going woth boost?
Those are two different worlds of power production, some concepts are simular and a lot are different.