I would call John at Outfront motorsports. He's the go to guy for high-horsepower subie motors in the offroad world and knows those motors inside and out. His website leaves a lot to be desired, but I would think its safe to say they're the equivalent of IPP or SZ for the subie world.
Outback Motorsports - 8071 Commonwealth Ave - Buena Park, CA 90621 Ph (714) 994-5222 Fax (714) 994-5633