Check to see if the breather and gasket are good.
My Briggs from a SJ flea market was one of three engines that were not running, and one without a carb, but for $25 who cares. I got Briggs 5S, 6S, and the 80202 0430 3hp now on my off road bike.
Post 63 on Page 7 pictures shows tear down of my Briggs where I replace gaskets and had valves and seats re-cut.
Post 6746 on Page 675 more recently noticed a lot of oil near carb and oil breather. Replacing the breather that was stuck wide open is easy fix. Part on Amazon was about $10.
Last page and pictures riding NOR CAL off road trails.