First off welcome to the forum, nice to see a post from a new member.
That's quite a tricky request as most people with MC engine won't want to part with a single piston.
To be honest I think you may have more luck over on the S2Forum as more people frequent that site and quite a few folk from eastern Europe on there do stuff with 10VT and MC motors.
Have you got a part No for them as it maybe interchangeable with another 10V turbo engine, though I think MC1/2 piston's are unique to that motor but I'm not 100% on that.