H22 timing belt, tensioner, and crank sprocket must be installed on the H23 block. (H22 uses magnetic triggers on the sprocket for timing, H23 doesnt)
dont forget to remove the VTEC oiling plug from the H23 block for VTEC to operate.
use any H22 headgasket.
it's just that simple.
and yes, i know what i'm doing, i've done it before, and i used to have a very detailed write up with photos, but that server has been gone for years now.