This kind of thing is one of the REASONS why rolling roads exist, if you have a set of verniers on an engine, then it is simply a matter of tweaking this way and that way, by minute amounts at a time, to get the best.
ALL engine work, tune ups etc are at the customers risk, obviously sometimes they can hit valves pistons if skimmed a lot(?), but this would be felt turning engine over on the starter anyway.
tabetha