do they will fit? flat pistons.

[Dziku]

I need advice. I've got some pretty 86mm pistons, but they are flat.
What CR i should expect with 90mm m47tu crank and m50 135mm rods?
An how deep should i do cutouts for valves?
Ah, copression height of them is 32.5mm.

Can anyone help me  with this?

Sorry for bad english.