F series trans for boost, the H23 is too short a gear for the low revving F series and we are shifting into fifth in the quarter which is not good for the F/H tranny because of the 5th gear shift fork mis-alignment.
phillips racing engines can sleeve the H series no problems.
the JDM DOHC F20B is just a USDM H23 essentially except the displacement, heads are identical.
The G23 swap is becoming more popular, search the link i posted earlier for piratemcfred who is currently the guy to talk to about that swap. All the G23 is is a F23 bottom end with H22 fitted to it