Sounds like oil burning to me. I would guess exhaust valve seals as the high compession of the engine would tend to burn it up otherwise. But it could also be rings or intake valve seals. My knee jerk reaction is usually to do a motor flush (be careful follow instructions) and if that doesn't fix it, replace the valve seals Fairly involved job, but possible to do without getting the engine apart.
The motor flush is a solvent (no viscousity when in the case so NO LOAD ON ENGINE) and often frees up stuck rings. Really easy to do. If it was injector/compression related, it would idle poorly. I would have first considered the turbo, but you replaced it. I would note, however, that most turbos will let a little oil sneak by during extended idling.
Often rings will get stuck after getting the engine hot. The piston expands and the rings are pushed into the carbon deposits, getting them stuck. On gas engines, the 3 piece oil control rings are often ruined if it gets that hot, but most diesels use a single piece control ring that is much more resistant to losing temper (won't spring out against bore) from excessive heat.
Another thing to note, is that some of these engines crack blocks.
How MUCH smoke? Noticeable wisp or steady cloud?
