Small gauge on the big pipe, big gauge on the small pipe outside at the condenser. The refrigerant type does not matter. Be careful when connecting and disconnecting the high side gauge. You can...
hook it up to the intake vacuum, normally the back of the carburetor where the brake booster may be plugged in. On a vehicle without power brakes, the vacuum port is normally plugged with a screw in...
I would suggest you try to find the manufacturer of your tachometer on the web and check out their support site and email them if needed for your particuliar vehicle. For instance below is a link to...