Shane,
I did not paint the case.
I only painted the door assembly and heater core holder.
I also painted the blower motor & cage and the motor mounting plate.
I reused the door assembly and heater core holder.
My door assembly need work. I blasted the door assembly then had the holes filled with filler.
I do not know if the door assembly is available?
I never got a response on what sealer to use and when I asked around locally everybody had a different opinion.
I ended up just using black RTV - so if I had to take it apart again I could.
I only used sealer on the big metal housing that attaches to the case and where the motor plate bolts to the metal housing.
I did not use any sealer where the case halves fit together.
Hope this helps.
Dale.