Let's set yopu on the right path here: You HAVE AC originally installed in a 86 IROC. You WANT to install NON-AC parts. Your Options are:
Install a replacement AC heater control.
OR
Install a 82-89v Non-AC heater core box, & install 82-89 NON-AC heater control.
OR
Install a NON-AC control from a 90-92 Camaro. ( Yes - the Yellow letter version )
You could than use the original dash housing and retain the extra air vents, or you could install an 82-89 non-AC dash housing and loose the extra vents. You could install a AC or a Non- AC heater box inside the engine bay doesn't matter. You could also decide to install the additional " forced Air" vent system from the 82-89 set-up or not.
You CAN NOT install an 82-89 NON AC Heater control to a AC heater core box. 82-89 NON AC controls are cable operated and 82-89 AC systems are vacuum. ( They are Not companable.) In the 90-92 cars the heater control is vacuum operated for both the AC and NON-AC systems.
I've got just about any combination of this stuff avaiable for sale. Re-read thru this message carefully and re-post here if you need more info.