The flatness standard for both the bottom of the carburetor and the top of the fuel tank is not more than 0.002" low in the center, measured with a straight edge across the carburetor or tank from side to side, and a feeler gauge in the center.
The choke preloading is done by opening the choke as far as possible (past fully open) and holding it in that position while doing up the carburetor-to-tank mounting screws. It is well worth servicing that carburetor with the Briggs & Stratton Service and Repair Instructions 1984, open in front of you. The specific automatic choke instructions are on pages 39-43.
A 92908 should start first or second pull, even after sitting in the shed for a couple of months. If it doesn't, it needs fixing.
