if you're using a .0005" indicator than i would really be cautious about the readings. you're using the bore gauge as a comparator which is a good thing but setting the gauge with a mic (you must when using the gauge as a comparator) is very touchy and that coupled with possible indicator and measuring error can lead you astray. if you're looking for tenths accuracy you really need an accurate (read not chinese) tenths reading indicator.

as for the .0025" if that is accurate it might be a little snug for a race engine. a little loose and you can be OK, too tight and if it rubs well who knows. lots of variables and i'm always concerned about tolerance stacking.

wish i could give a definitive answer but without hands on i'm only guessing.

i'm completely anal OCD about measuring stuff and am never satisfied