That gasket shouldn't need sealant, but the surfaces it clamps against on both sides must be clean and flat. Be sure the carburetor flange is flat: they sometimes get bent.

Here is the Illustrated Parts List for your engine:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6jmvGVJ1DajI.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/lrvvA-wU7eL7hAxB91ObQ.pdf

The engine was made on 16 June 1973, so it's been around a while. It has a Vacu-Jet carburetor, which is a rather simple design and easy to work on. You can see an exploded view of it on Page 5 of the IPL.

Note the strange pull-device on the left side of the diagram. That is the choke: you pull it out with your finger and thumb, and it will be so totally choked that the engine will rich load and stall in about 5 seconds even if stone cold. However when you choke it and pull it over twice it will start, and you have only 5 seconds to push the choke all the way in before it rich loads. If you have been trying to start it from cold with no choke (that is with the choke pushed in, as it is in the diagram), you have no hope of success.