NXS C-15 Problem

alright some background on truck is that it was bought by me a few months ago in mississippi as a truck with fresh rebuild due to being "dusted" so I assume whole top end torn apart and looked at. It only has 257,000 miles on it currently. I probably put on 1500 miles as is and thought it was a real dog at 475/1850 and had a good amount of blow-by and oil smell around truck, the used truck dealer in mississppi said it was due to rebuild and the rings needing to seat, alright i guess. well a couple days ago I put the boost and fuel temp mods on the truck, helped a good little bit on the power and put a couple hundred miles on that setup. then this past Wednesday I had truck up rated to 550 heavy haul, hauled 60 miles on that and really liked the added power of the up rate and fuel wire mod. The next day I added the bully dog HDGT tuner on power/economy tune. The first day I got to use it like that was today for about 50 miles before the big problem hit. I was just done pulling a sizable hill for my area and noticed what looked like the gravel dust being thrown up from the gravel on the shoulder but it didn't go away if i moved to straddle the center line and was quite heavy. I stopped and opened the hood to see the radiator cap must have let pressure out as water everywhere under hood but not actively leaking. I then restarted truck and looked again to see the blow-by tube billowing out white smoke and smelling sweet like i have been led to believe anti freeze smells. everything was in check gauge wise (had same oil pressure, oil temp, water temp) so I continued the last three miles to the farm and unloaded my end dump, smoke still billowing out of blow by tube. shut truck off and go talk to a guy for 20 minutes about it and go back out to start truck. this is a no go and its locked up tight. I unhooked it and yanked it out so that its ready to take to CAT on Tuesday.

I guess my main questions are, would any of you blame this on the additional power of the bully dog? I'm inclined to believe the Mississippi dealer did a hack job as they are not certified anything and the only reason I went through and bought the truck was the one year warranty on the engine work which they better not give me any trouble with redeeming.

Also whats the best guess on the damage? I didn't see any white smoke out the exhaust so I'm a little confused on how i would get locked up if there wasn't much if any coolant making it to the cylinders. Also I understand basic principles of these engines but where was the coolant getting to that burned it off and sent it out the blow by?

Last but not least, if they rebilt it for some scored cylinders or sleeves or whatever, and now this (most likely head gasket? but is that all?) what should I have the CAT dealer check on the internals to make sure everything is in check after the Mississippi shop messed around in there? how in depth should I have them look while its opened up?

thanks,
Jake