The P08 is the JDM version of the P28, and there are small differences in mapping for the different country. Either ECU will work fine for a SOHC VTEC swap. If you have a P08, use it; it can be chipped the same way as a JDM P30, the parts are just a different size than the USDM. If I remember, the P08 is the same ECU as the (JDM) P30 but without the knock sensor board. There is no need to get a P28, you already have it's JDM twin. It's actually identical inside, the parts are just smaller (surface mouton parts instead of through hole) which is the difference between the JDM and USDM P30s...

So now you know..