FYI, the stock 02 WRX engine is called an 'EJ205'. But I'm confused here, are your heads in good shape or not? If they are, there are a lot of shortbock options. I would suspect the EJ206 shortbock would work with the EJ205 heads though you'll need to research that. If your heads need to be replaced, that ties much more with the ECU/harness and you'll have a more complex choice if you can't find another EJ205 but if your heads are still good, you have other choices by making a hybrid.
2015 STi: Still Stock
04 STi, 04 WRX: SOLD