1973 duster heater assembly

I have a 1973 Plymouth duster. Previous owner removed the heater box/core and control arms from the vehicle. The dash selector switches are still there and in working condition. I am looking for the necessary pieces to put the heater back together. I have a new blower motor but not the fan wheel. I will purchase heater core and lines new. I'm assuming I just need the box and necessary pieces. Thank you for your time!