swaping ac unit. Help!

I have the entire 72 dart here in my driveway, I bought it from the wreckers for 800. My 67 dodge dart doesnt come with ac so I knew I was going to be cutting some holes in the firewall. But I am wondering about the controls for the ac system. I found a couple places that price the little piece of plastic for 150 bucks for my dashboard unless you know a better place. Thanks for the info