I have done this, friend of mine put an 02 motor in a 98 mtn srx.
You need ALL electrical, including the 02 panel with rheostats for the warmers, also the seat plug for the tail light is different. you also need a dual bulb windshield and 02 gauge pod with the DCS light. You will have to drill an extra hole for the 02 CDI because it is wider and the bolt holes on the 98 will not line up with the 02 CDI
you will have to drill a hole or find a means to mount the servo motor where the 02 has it unlike the 98 where it was mounted on the air box.
Your looking at 4 years of updates in the conversion
Do not attempt to use any electrical from the 98