I have a '67 deville with a 429. the brake check valve hose and the PVC valve hose are both loose on the rear of the engine. There are only two places where these hoses can go (2 open ports), one is on the crankcase and the other is on a manifold cross-over just to the rear of the carburetor, above the crankcase. I don't know which goes where. This may be why the car will not start. Anyone, please!!

 

That big of vacuum leak would cause no start. Figuring you have a Quadra-Jet Carb the large port in front of carb under filter would be PVC the one in the rear it would be a screw in fitting would be for brake booster.