I will assume you are talking about a deluxe fresh air heater, the type that is attached to the side wall of the cab and sucks in air through the louvers on the right side of the cab. The Chevrolet Accessory Installation Manual has good drawings of all the hookups and parts, along with written instructions on installation. Heater control valves are on ebay every once in awhile, I found one once in a junk yard and got it, sold it to a friend. Those kind need to be rebuilt, which entails a new rubber seal, available from chevy duty, but the package it comes in says "NAPA", I would check there first. Switches were not reostats, but the click on,click off light switch type. Vintage Auto Parts has some, or did. I do not know of any other place that sells them.
