Bore for larger cylinders such as what is called thick wall 90.5mm that have the same OD size as 92mm size, (head studs removed). This includes first boring the spigot 1mm larger than the piston size to the bottom of the case hole with proper radius, bored for cylinder size part of the way down (step boring) with proper radius, and then decking the case down 0.060" to achieve a full flat surface for the cylinder and/or spacer to seat on. This function has 3 separate operations often called step bore and face. This is the only way to achieve full seating surface for the larger cylinders and to provide maximum life. If you are getting a case from someone else, make sure they do the same machine work. I suggest you ask them how they do the job and see if it matches what we previously described. If not, get it from someone that does it correctly. The engine life depends on it.