Last year I detonated my blower motor badly, with all the blower noise and all I couldn't tell it was happening until my last run when it laid over on the big end, and started blowing by, really bad. I tore it down, seven pistons were melted at the edges, even damaging the cylinder walls. It hammered the pistons, forged JE's, so bad it compressed the ring grooves to where I couldn't remove the rings. I never had any blow by before that, with gapless rings and not even a PCV system. An expensive fix.
I don't wish that on anyone, but if the leak down test comes up with problems, pull the heads for starters and have a look.