YES for getting engine life you need piston oil coolers with a turbo however if your just gonna drive the truck around and not work it it will probably be ok. it takes a load on the engine to build boost. i,am also concernned about the really small oil cooler. its the smallest cooler i,ve ever seen on a 855 engine.
I'm still confused with your posts. You asked for the best turbo. Then asked how to install squiters, then explain what has been stated, then revert and make an exception.
Here's the highpoints:
HT3B is the turbo to use
NHC 250s do not have oil squirters
Squirters are not easily added
Squirters are inside the block
A small cam nhc 250 cannot safely put out extra power above the 290hp mark without driving by gauges
A big cam will provide more power safely
Any diesel fueled beyond factory spec can fail or have a shortened lifespan by careless operating.
A NA diesel can be turbocharged, IF, an understanding of the limit is observed at all times.
Do you have anything else your wondering about or need help on?
FWIW, I speak from experience, owning the combination you're asking about. As well as other NA turbocharged engines lacking the Squirters. It's all about defining limitations from the start and adhering to them. And driving with a brain and not a lead foot.