might as well keep the 85 in. Both are 2.2s. The 89 T2 has the charge temp sensor, but its not impt. And unless you manually run a wire from the sensor to the ECU (since the 85 harness wont have that plug), you'll have a check engine light to stare at.

And yes, you'd need an 89 Omni harness b/c it's SMEC like moreRICE said. I just woke up so im not thinking. But if you get an 89 omni harness, it wont be turbo so some things might be off there. I'd just use the old one since you'll be doing fuel and boost manually anyway probably