If you have a 97 GSR, then put in the OBD2 ECU, period.
Why did you buy it with all of the problems? Did it drive at all?
And, why did it come with an OBD1 P28 ecu in an OBD2 car? I'm lost...

Your car will die/won't run with the Crank position sensor (CPS) busted...
The ECU won't know what degree of rotation that the crankshaft is in, so it won't know when to fire the spark. Although this doesn't sound like it is the sensor, just some kind of problem you are having cause you don't have the right ECU...

Good luck!