67 A/C heater box rebuild and install help

"cooling?" If you mean heater, you can just run a hose from between the two heater outlets on the engine. This WILL bypass some coolant, so you might want to stuff a scrap stud in there to block the flow. Don't forget to fill the cooling system with the heater connection up on the manifold open, so that you can "burp" the air out of the system

You should not need to hook up any of the AC stuff, unless you need to mount the pump for the belts. In that case you do need a good compressor clutch (bearings) to act as an idler.