If one cylinder is oversized by .010" , the opposing cylinder
gets it, too. The heavier .010" oversize piston will throw everything
out of whack otherwise.
A one-pound heavier piston would run satisfactorily to someone
else, not to most of us. It would shake pretty good. Might get you
home, but that's about it.

A .010 inch oversize piston doesn't necessarily have to weigh more.
And the piston area is less than 1 percent larger than standard. I
don't think that would cause a rough engine, as typical ignition
timing and mixture distribution variances will be much greater than
that.

But, a single 1 pound piston mass imbalance would give a typical
engine crankcase vibration of about 3 ips, which would obviously be
pretty rough to most of us.