You have another bad LLY head gasket, they all do it eventually. Their really no different from the lb7 and it's injector issue. You just have to deal with it, just fix it right the first time with grade c gaskets and arp 625's it isn't gonna be an issue again. I know it's frustrating but it seems like you got a killer deal on it anyway and it woud cost a lot more to replace it than fix it...
Tell that to the contractor who lives around me with his 450k mile all stock never touched 05 LLY.
Or the lawn maintenance guy with 375k on his stock 05 LLY.
Or my own truck that had almost 100k of big single and twins abuse, hundreds of quarter mile passes, 50psi++ boost, etc.. I lost a couple pistons, the head gaskets were fine when I tore it down.
They arent "ALL" going to do it. This is nothing like the LB7 injector thing.
And WTF does he need ARP 625's for? You dont even know how to work on these engines, so why are you throwing advice around for parts you've never even touched/used?