New motor gone...

The motor **** out on me while giving it some test pulls. Trying to figure out what went wrong. What are the chances my Mallory 685 isn't pulling timing correctly? Engine is 408 with 9.1:1 compression. Was only at 8 psi boost with air/fuel around 11.5. 93 pump gas running air to air intercooler. Complete forged bottom end from MRL Performance. It all of the sudden started running like crap so got is towed home. Started pulling plugs and the #1 piston is beat all to hell. Not sure if it's cracked or a completely blown apart yet. I was pulling 1.5* per psi with the Mallory 685. I don't see how I could've had pre det as that should be more than conservative if timing was pulled correctly. I know some guys on here run the same ignition so perhaps someone can give some ideas. I still need to pull the head to make sure something didn't drop into the cylinder but I'm confident that isn't the case. I've been building this motor for a year and have less than 3 hours on it.