A thicker headgasket effectively increases the volume of the combustion chambers thus raising compression ratio. Shaving the head would obviously be counteracted by this.

You wanna see a dome piston? Look at a CTR piece. All a domed piston really is, is one with a positive dome displacement. Dished is negative displacement, flat-top is "no" displacement.

I think the main point is that he wanted to practice doing the machine work and wanted to know if there are any ill effects.