So what I'm seeing is a melted spot on the piston. It's on the intake side of the piston. This is telling me that you had a fuel delivery problem on that cylinder or all of them and this one (and #1?) succumbed to the lean condition.

Also, you mentioned that you had a fuel level sender issue filling up the day it blew. Do you think that you fuel starved the engine from an issue in the tank? High G's of the event might have exacerbated any marginal tank problem that could have existed.