Hi
I have had a few Detroit's over the years.
Myself i would replace the turbo.
I don't follow the logic of how the block could get broke by adding a new turbo.How is the supercharger? That should show you if there are more bits floating around.Mine had a screen before the supercharger to catch bits before they went through it.
The 71 series of Detroit's are one tough engine.If the airbox's are clean go with a new turbo and let her rip.
I was told by a senior trucker before driving a Detroit you need to slam the door on your hand so you are pissed off and drive the crap out of the truck.
I had one in my fuel truck that leaked oil out of the air box's when it was started.It would leave a 6" puddle each time it was started.Another old-timer told me to stop using multygrade oils in it.So i switched from 15W40 to straight 30W the puddles disappeared to a few drips at startup.
The scariest thing that i was witness to was when my mechanic changed injectors.He didn't get the rack set right and the 671 ran away.Tanker was about 1/2 full and all i could vision was a huge explosion in my shop.He was trying to smother it with a piece of plywood over the intake.I managed to spin off the fuel filter and got it shut down before it exploded.
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews