there are several different Puch 1.5 hp jet setups..
1/12/293 = Maxi 1.5 HP main jet 60
1/12/309 = Maxi Luxe 1.5 HP main jet 48
1/12/321 = Sport MKII and Newport 1.5 HP main jet 50**
The carb size doesn't make that much difference... it depends on the engine... I've tried a 12mm and a 15mm on my Newport 1.5 hp with a 12/14/15mm intake and the jets were the only factor that significantly changed the performance... and the plug in/out of the back of the airbox!