With the B7 you don't need a P28, if that's what you have. You could probably sell it for some cash since it's desirable and get the correct ECU for the engine (I would definitely be willing to trade you!).
It's probably safe to say that the stock D series was pulled and the D15B7 was thrown in it's place, keeping it OBD0. You more then likely are running the PM6 ecu. Nothing wrong with that for a SOHC non-vtec.