Hey you can build a block for 500HP easy all you need is a good block,pistons and rods, you dont eve need to get the motor sleeved, alot of people make 500plus on stock sleeves.Peter made 580HP and ran for 1 year on stock sleeves,i have even seen 650 on stock sleeves....

the list of stuff you need for motor.
CP pistons 9:7:1 $450
Crower rods $400
getting motor honed and decked $250 tops
Bearings $100

now the head
Springs and retiners $250
Type R cams $300

thats $1750 besides turbo kit and buying the motor!
with that setup you can hit 500HP!!