Cumming ntc400 big cam. Need help!

NM will probably have that coming to you after some work but that is above my skill level.
NTC400's made around 1986 and 7 smoked a lot cold when they were new.
The turbo air outlet connects to an orange hose about 3 inches in diameter. On your model I believe it connects to an aluminum manifold that goes over the center of the center valve cover and bolts to the after cooler, on the drivers side, with four bolts. If you remove those four bolts, with a 9/16, there should be no oil inside.
If there is oil there the turbo may be bad but check the air filter and for a restriction and the turbo oil return line which can also cause that.
Take the big connection off the front of the turbo that goes to the air filter. If the impeller inside is rubbing on the housing it is junk.

 

If the breather was plugged it most likely will push oil out the dipstick.
After you check turbo. Get the motor up to temp,pull the oil fill plug,put you hand over the hole,if it feels like someone punching your hand. Then probably a broke ring,scored liner etc.