it should work in this case, but the fuel maps will be off, and you will need to chip it.
the USDM P72 has a controller for butterflies i don't know if you'll get any codes or not from it because I don't know if anything was done with the P30.
your saying its a 97si and its OBD1 stock? Unless you have a OBD2 P72. Do you live in the US? there were not 1997 Si models here other than the del sol, somebody just rebadged it.
Just check near your feet that you didnt kick anything out, and make sure its not your VSS sensor in your transmission.