I'm pretty sure that the JDM B20B is identical to the USDM B20Z, but I'm not 100% sure. The way you can tell is if there's a number at the end of the engine code, like B20B4 or something... JDM engines end with a letter, USDM has a number after the second letter.
With a B16 head, you can make any amount of power... custom engine builds don't have specific power levels.