"Measuring at the middle ring, I get 93.4 on the piston. The bore is 93.7 in several spots. "
Measuring at the ring lands is why you got the measurements you did.
If you put a straight edge up against the piston you'll see how far the ring land area is recessed from the rest of the skirt.
Pistons are at their smallest at the ring lands.
Your machinist picked the right spot.