Maybe you can help me....I sure Hope so!!!!

I am restoring a 1977 ATC 90 and I am trying to sort some things out. I gave my cylinder to a friend who works at a Honda dealership. He ordered a piston and sent it off to the machine shop to get bored. Once completed I began to assemble the thing to find that the piston pin of the new piston was to large. It would not go thru my 90cc Conn Rod. The shop where the piton came from is telling me that the piston they ordered is a 110 piston. So it looks like my cylinder is now bored to be a ATC 110 piston. What can I do to fix this? Some people are telling me that a 110 piston will work...but how? I can't see how this would work as the 110 piston I bought uses a Pin that is to large for my Conn Rod. Was there a production change or some thing? Will a certain year 110 Piston work with my 90cc Cylinder? Or do I need to get a new 90cc cylinder or change out my 90cc Conn Rod to a 110cc Con Rod. Please help!!! as I am beginning to think that my cylinder is no longer gune work on my 90 with a 90cc Conn Rod.

Thanks in advance!