How many passes did you make? I used the same technique with a little fresh engine oil just to prevent it from ripping into the cylinder walls and, although my bores weren't vertically scored like yours are, I managed to completely de-glaze the surface (might need to use a coarser finished pad... I tried with the spring loaded stone tool and I was scared that it was too aggressive so I gave this method a shot) If you are going to hone it you may be going beyond the tolerancing for 'stock' pistons and rings. I think the rule is that if your thumb nail can catch on the score marks, it's time to rebore the cylinders.