Thanks for your answer, appreciate it.
You are right, will not go with KB190.
Instead, it will be 4inch stroke with flat top piston(diamond 5cc). 12.5cr will be easy to achive.
If piston protrude, I will compensate with thicker head gasket and target quench of .045 inch.
Thanks again

Is there any danger if piston protrude, how far out can it go without issue?