Just Purchased Virgin 340 Short - What to do with Pistons

No offense but if you are assembling it yourself, then you should be able to figure out compression ratio. It's a math equation based on measurements of your motor and gaskets. I'm in same situation as you. You'll get satisfaction doing it yourself.
Google Wallace compression calculator.
Give it a go and post your results.
Someone here will double chk results.
Hope I didnt sound like a dick.

No offense taken, it's just that many people have info at their fingertips, and just tweak a value or two. I would have to research what the cc's in the piston are for stock, as well as typical deck height, which is never accurate. And so on. Yes, the calculations are easy peasy