FROM THE CARB AND MUFFLER IT COULD POSSIBLY BE A CLINTON OR LAWSON ENGINE OF EARLY 50 S VINTAGE . BRIGGS USED MOSTLY ZENITH CARBS WHILE LAWSON AND CLINTON USED TILLOTSONS- JUST A GUESS -GOOD LUCK - RICHARD
sos if you notis in pic 3 thers a pin stiking out abuve the flywheel ther is sopsd to be a aluminum blade on it wich is the guvener for the throtel on the carb if you need more help just pm me regards bob