Thanks Stanton,That is what i need to know.
Then the CR would be around 9.6 :1 using a 0.027 gasket

Your impressions about the block deck are right.Someone deck this one in the past, ,0.025 or so.This does not allow to combine a wide range of pistons cause almost all of them are 2.060 CH and they would have an excesive negative deck.
The one and only piston change solution is the 1.991 CH piston,wich would get a zero deck and 10,1:1 CR.
That is why i don,t want to deck the block more than it is.

Thanks