How much should I remove?

[DaveO]

Sorry if this has been discussed before, I tried searching but couldn't find exactly what I'm looking for.

I have a '69 Camaro w/ factory AC. My question is how much of the factory equipment do I remove if I'm going to replace it with a complete aftermarket system? I haven't decided on which system yet, my only requirement is ability to use the factory controls. I removed everything in the engine compartment, but do I also remove everything behind the firewall including the heater/defrost, selector, and distribution assemblies along with all ducts and kickpad valve assemblies?

thx in advance!