[WKB]

There would a fair bit of work modifying the tunnel and firewall. Even if you completed the mod I still think the motor would be too close to the firewall to attach the heater and air con pipe easily.
Although the DRB aircon is not as nice as the OEM due to the air control/ air mixing of the Falcon air box, it is intgrated and the air con, fan and heater are controlled from the dash.

Warren