Hi Paul. First, that engine was advertised as 10 hp. Here are the Operating and Maintenance Instructions for it:
http://bsintek.basco.com/BriggsDocumentDisplay/msowHM-K_ny7tH217FzoPu.pdf

Here is the Illustrated Parts list:
http://bsintek.basco.com/BriggsDocumentDisplay/18mqvGXAnfBhU7y.pdf

That is a large two piece flo-jet. The high speed jet (sticking out at 45 degrees low down on the left side) should initially be set at 1.5 turns from fully clockwise, and the idle jet (sticking out horizontally from the right side) should be 1 turn from fully clockwise.

As a sort of rule of thumb, if an engine comes to you with the settings ridiculously rich, the previous tenant had probably set them that way because the jets are seriously crudded up and they needed to be set ultra-rich for the engine to run, or the fuel line or filter is nearly blocked so the engine leans out as it runs, due to the float level dropping steadily. Also, in your picture the high speed mixture needle looks as if it is badly bent.