Replacing 67 Camaro Heater Core

[Zedder]

I want to replace my leaking 67 Camaro heater core and there appears to be two ways to do this...remove the fender and access from the engine bay, or remove the glove box and drop the heater box into the interior and access the core from inside the car. Since I have nice paint, I'd prefer accessing the core from inside the car. Anyone ever do it this way? Any tips or pointers that you can provide? Thanks!