OK, that case has no vacuum servos or anything else that may have failed other than the heater core. DMT offers a complete reseal kit. There's no reason to pay anyone else to clean and refurbish that case. The climate controller, cables, and door operation should be checked over and lubricated.
Its electrical consists of a blower motor, fans switch, and fan speed resistor stack, all of which can be replaced as needed.
If you had the 67 a/c case with that troublesome push button controller my responce would be totally different.