Air should flow towards the engine.

So if you can blow into it and air passes through, the end in your mouth is the end to the controls and the other end goes to the engine.

There should be a fitting behind the carb with the brake booster hose on it. It will have a separate small port for a hose that goes through the firewall to the check valve and then to the controls.

You may check that hose also to be sure it is still good. Age gets to them a lot.