Ok first the embarrassing question. Putting it back together, is it possible to put piston in wrong? (180 degrees), it is a 2 stroke.

The story behind this motor is the man that started mercury motors found a bunch of these in warehouse he bought that were returned by customers due to poor starting. They say this man changed type of carborator from poppit to something else. QUESTION, does anyone know what type of carb he would have used. I have no idea how a poppit valve even works. Any info would be helpful. I know it ran 50 years ago when I was out in the boat with my dad. But has been sitting on a shelf a long time.