Just Purchased Virgin 340 Short - What to do with Pistons

Great, I was hoping there would be a general consensus that stock pistons are fine, I was just checking to see if I was missing out a bunch on modern new pistons, which I know nothing about.

So, next question, I have 65cc heads. It will take me some research to see where I would be with CR......does anybody know have the calculations handy, to report back where my CR would land? And assuming it is close to 10.5:1, how is that OK, when everything I have read, suggests I want something close to 9.5:1 with iron heads? Would I not need premium fuel or higher?