Not that you would want to pull the head again, but you could give Cummins Rocky Mountain a call and ask for a thicker 3rd Gen gasket. Common rails have been in use for a long time in commercial vehicles so you would think they make 3rd Gen head gaskets in assorted thicknesses for their engine rebuild kits. Just about every high mileage rebuild will require a shave to some degree.

 

No it is not. These guys are foolin with you. Look at the formula to figuire out displacement. All you need to know is bore, stroke, and number of cylinders. And you did nothing to change any of them things. All you did was very slightly increase compression ratio, and move the valves .006 closer to the pistons. Like I said, if it was a good machine shop they may have even sunk the valves .006 to keep that distance the same, as well as keep your valve adjusters close to where they were. But even then I doubt you would notice .006 difference on the valve adjusters.