Round head Pico engine. What supplier options do I have?

I have a pico 49cc motor that needs a new cylinder and piston. My distance between head studs is approx 43.5mm

40-41 mm bore 36mm stroke approx


round head, 6mm studs


Does anyone know what cylinder and piston kit I need to purchase?


Thanks!

I have a picture of the cylinder and piston in this thread

http://motorbicycling.com/showthread.php?t=40286&page=3