Help me with some math Please

You need about 100cc of total combustion space to reach your goal. With 85cc in your heads, the rest will be your head gasket compression thickness and your piston deck height/valve relief volume. Assuming stock stroke and .035 or so head gaskets, a flattop piston down in the hole about .030 would get you close. There is a ton of info on here about figuring all this out. I use 3.14 for pi and 16.39cc per cubic inch. Pi x radius squared x stroke gets your cylinder volume, then cylinder volume + combustion space divided by the combustion space alone gets your compression ratio.