under dash wiring harness

I have an 85 lx that i used a complete harness from an 89 speed 5.0 donor car. By complete I mean from bumper to bumper. I did this way back in the 90's. I now would like to put the original 85 2.3 lx 4-cyl, with a/c, dash back in. How complicated would it be to integrate it into the 89 harness...

Hey y'all, long time member/stalker, here on the west side of San Antonio (just outside Lackland) first time poster....I started with an '03 v6 with the pony package, but sucked water up the intake. I was lucky enough to pick up an 01 convertible for $500! Of course, it wasn't in the best...