where to find a new piston for 40mm stroke crank?

i need help finding a piston for the longer(40mm) stroke crank shaft, the wrist pin thats higher up on the piston.

http://www.ebay.com/itm/160803240873?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

thats the piston i need and i bought it but arrived today and was the piston with the lower wrist pin hole... 38mm..

I'm not entirely sure it's a 40mm stroke, it may just have a longer rod (40mm stroke makes it a 70cc motor). Look for Skyhawk pistons, they use the higher wrist pin, I bought a new one from a new vendor and got the low wrist pin so I couldn't use it. Since you're in Michigan, I dont think you'll be able to order from www.motorizedbicycle.ca, but... ya never know, thats where I got my first 3 kits, and all have the higher wrist pin. I dont know what all the hate is about on grubee skyhawks is, I've had 3 and none have broken down on their own (one was stolen, one lost to a fire, and my current one breaks down because I tend to forget simple things), to my knowledge all kits are the same random "quality", aside from pretuned ones.

are these pistons/cranks typically harder to find?