Just saw this. Car looks great. A worthy tip on rebuilding heater boxes once all cracks are repaired is to lightly glass-bead blast the case, then clear coat. Makes them look like new.
On the decision to bead blast before paint, was interior removed? I bought a Mach1 that had been blasted before paint and as I disassembled the car for restoration that abrasive media was everywhere. It was in the dash, headliner, etc. I was blowing that stuff out off the car for weeks...