NO NO not the squares (rectangles actually). Those are where the bolts go in to hold the torque converter to the flexplate! Oh, never mind you mean the thin square on the outside LOL. I actually don't know what that is....
As for the triangle, I would not just wedge it off for fear of breaking the metal underneath. It would be tedious, but I would carefully grind down through the weld.
And yes, your flexplate is the 360 external balance one. And has an SFI sticker on it too.
