lots of questions,
1. no there are not stamped as to left or right, the number is left or right. I can goto the shop later and take pics of my pistons and try to figure left or right. You CAN see the pin offset, or you can measure from the skirt to the centerline of the pin.
2. 327 rod is STRONGER, i can take a pic of the 327 rod I've got.
3. ball milling is just a preferance as to the machine the engine builder/balancer has. I would not ball mill, it can go too deep into the cap and make it weak.