1971 340 L2316 pistons stock, modified or damaged?

I picked up a 1971 340 a couple of weeks ago and I was wondering about the markings/grooves on top of the pistons. I'm not a expert on building engines or pistons, but I was curious as to whether the previous owner had cut into to them or possibly installed them incorrectly. I included a picture of the same piston being sold on ebay. Either way, I plan on stripping down the block and starting from scratch. I plan on using the stock J heads with the rebuild.
Let me know what you think.

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L2316 piston.jpg