I have an 85 El Camino that I'm deleting the A/C and installing a heat only box because of installing a BBC motor. I want to install a 78-81 dash. My question is, will it bolt right in? I want to eliminate the center vents and keep the end vents. I know the ductwork is different for heat only. Is it different for the different style dashes? I'm going to get either, a) new dash from OPGI or b) get an old core and have it restored. Thanks for any help or information.