If it were here, I would use a manometer oil the oil fill to check crankcase pressure. It should be less than 4 inches of water column. You could just flip your oil fill cap over. If it blows upward pretty good, yes, you have excessive blow-by. As to vibration, you said he was drunk. He might have gone full on yahoo, took it off road and did something to the driveline.
You need to isolate engine from driveline. Get it up to normal operating temp and take it slowly all of the way up through the RPM range in Park to see if you have vibration. If you do, excessive oil during the drive may have camebup through the breather, took the trip through turbo, intercooler, and into engine. If it got a good enough dose, a rod or two may have bent a bit. That would shorten the stroke a bit. This might be detected through cylinder comparison or measuring down to the piston through the glow plug hole.
Rods aren’t the end of the world. I don’t see ring blow-by being caused by an overfill.
Muffler may have a ton of oil pooled up in it and will smoke forever until it gets drained or burned of. This will cause an exhaust restriction which will effect performance in RPMs above about 1500 RPMs depending on how much is in there and they can hold an awful lot.