Why not look at an EJ207 swap? The EJ207 is the STi motor for the rest of the world. It is a semi-closed block like the USDM 2.5, it can have a twinscroll turbo (Version 8 and above), AVCS, big port heads, etc. It also spins to 8500 with ease, day in and day out. The 2.5L... not so much. It's a fantastic motor, perhaps the best overall EJ built. They also are WAY less prone to piston failure like the 2.5L. Best yet, EJ207's drop into the 02-05 WRX's so easy; they are nearly plug and play. No joke. Do a bit of searching in the 2.0L technical forum and see.
You can get a FULL EJ207 swap with the STi 6MT trans for $5600-$7000. On the higher end, they include the Brembo brakes and STi hubs/axles/etc.