And why would you want to? $7,000 is the cheapest I have seen one of those motors go for. A 90* v6 with FRM cylinders? I'd take 60*, Iron sleeves, VCM, i-vtec, and 3.5 liters any day. Throw in a turbo kit and you still have $2,000+ in your pocket.
Wiseco makes a 10.4:1 piston for the J30, but with an increase of only .4:1, you wouldn't see much of an improvement, especially for $600. You can always get some made to your specs, but custom pistons are even more expensive.