Diesel Bombers - 6.0 that no one can seem to figure out

So I'm working on my buddy's 6.0 for him I'm a certified diesel tech but have yet to figure this out. I've talked to everyone I know and even my buddy that's a master tech at the dealer. So here's the story. Someone was driving his truck and wasn't paying attention what so ever and the truck ended up spinning a few bearings and cooking everything else. So I junked the motor and he bought a used one. Got it In and try to start it and it cranked for ever. Ended up having high pressure oil leaks and a bad HPOP. Long story short I've replaced the hpop, ipr, icp, standpipes, dummy plugs, p/s oil manifold. And 8 injectors. Now it'll crank for a good 20 seconds spit and sputter then fire up and run like crap. Missing pouring white smoke I mean filling up my shop.. Until I unplugged certain injectors the miss was there but smoke was gone. So then I replaced 8 injectors with "good" used ones he had. Also when I replaced the hpop it was a "good" or said to be. Used one. Now I get it running and it does the same exact thing but stops pouring white smoke when I unplug different injectors then last time. I feel like it's a oil pressure issue (weak hpop) because it won't start unless I inplug the icp it won't get 500psi to start and I replaced that sensor already. But once it's running and I plug it in it reads properly. And I checked the ipr duty cycle when it's running and its normal. Not trying to compensate for a oil leak. I also feel like it is bad injectors still at the same time. I tested the Solonoides on the injectors and they are good. Also replaced both fuel filers and checked the fpr and it was not sticking at all and swapped in the pcm off my truck and it did not change anything. Also swapped in my ficm and it did not change a a thing. I'm getting proper readings on everything I look at. Has me stumped and I need this gone asap!! If anyone has any input at all feel free to chime in I would greatly appricate it. Thanks