if i were you id go a whole nother route.....
id buy a ls bottom end..... build it with pistons and rods..... gsr or ls whatever you prefer. id say about a grand for this when your said and done.
swap on you si head and youd have a mean turbo build.
id go with an ebay kit..... but you need to piece it together....
cast mai.
t3/4
ebay intercooler an dpiping kit..
you get the point....
boost it to 15lbs or more...
youd be well over 300hp reliably.
i did it.... just not to 300 yet 230 at the wheels on 10psi