So i finally have removed, disassembled and cleaned my engine block, and was going over the block looking for cracks or damage and found these inwards facing cracks into a few piston chambers. only two have gone all the way through but the rest shows signs of wear. This is on the crank side of the piston chambers. How serious is this? Can it be repaired or is this not a fixable thing. I believe this was the source of the burning oil which led me to the engine rebuild in the first place, I have a video of it here
Piston Wear - YouTube

 

Your best option is it take it to a machine shop.I couldn't really make them out that well.A shop can tell you every thing a but the block an weather or not it can be fix.