If the cylinder was opened up .010 the std piston would be very sloppy in the bore.
Possibly someone was mistaken?? or you were given a line of B.S.
Happens all the time, the term "it was all rebuilt" is about as misunderstood/misleading as "if you don't like you can return it" @ a restaurant
Then there are some ppl who think a couple of gaskets and some spray paint describes the term also.
possibly the bore was in decent shape and it got new rings?
Did you actually measure the bore? That is the only way to really know what you have.
But if you are happy with the performance,no problem.
Some service manuals state a bore if round, it can be as much as .008 oversize and still use Std rings, I don't like that much clearance.
