If it starts and runs, I really doubt that there is anything at all wrong with your engine.
Take it out and work the livin' snot out of it for half a day and I'll bet that "blowby" business clears right up.
Diesels just don't like to run anything less than full bore, full tilt, heavy load.
I have a German 310 that was doing the same exact thing as yours when I got it. Two days on a 14' disc stopped all the issues and I have not noticed any excessive blowby in 7 or 8 years now.