Thanks guys. Don did a video where he took a '69 dash apart to get to the heater box. Guess the '68 heater box is easier to get to. That’s a relief…although I am under no illusion that getting the heater box out will be easy.
Still not sure whether to restore original box or go with an a Vintage Air box with modern controls. My evaporator coil does not seem to hold a vacuum so it may have to be replaced or repaired if I keep my original box.