Shaving

You really need to determine the use of the vehicle, and what octane fuel you can live with. Decide what CR will get you there, then make measurements to determine how much to mill. You can't run 9.5 CR, with a stock cam, and stock dist curve, on 87 octane.
Not a major issue on the 198/225, but should ALWAYS check piston to valve clearance on a 170.
There are some builders who have milled he block .100 and angle milled the head .100 on one side, and .200 on the other side. Not for the faint of heart.