It is generally good practice after disturbing the piston or cylinder, to remove the ridge from the top of the cylinder bore. Even when putting everything back as it was, you can never be sure the piston will stop exactly where it did before. Since there is a 50-50 chance it could travel slightly further, it will of course do so 99% of the time! It only takes the piston to stop just a few thousands of an inch too far, for the ridge to beat the rings to death. They make ridge reamers for cars to do this task, but I have not seen a smaller version for motorcycles, though I imagine such are made. You can ease the ridge down with a fine file and finish of with some emery cloth, with much the same results.
However a 0.05mm step (0.002") is not all that much to worry about; 0.012" might be the point of thinking about a re-bore. 61.4mm is 0.024" over standard (60.8mm), so I think the +30 over pistons have been turned down, there has been a error in measuring the bore, or the pistons are out of another bike using a 60.5mm standard bore.
-Doug