I'm sorry for making another PCV related thread, but i feel like i am through most of them on multiple Forums and running out of ideas here and need help, i was unable to find anywhere else.

About a year ago i bought myself an 01/1994 850 T-5 Estate with 350k km on the odometer and am currently nursing it back to health.
I am young and not exactly a subject matter expert, but i am a (Industrial, not automotive) Mechatronics Tech (and by now a Mechatronics Engineer : ), so i do my own work.

When i got the car, I did the PCV, more as a precaution than anything and after a few other things (and several 1000+ km trips) i decided to seal the cylinderhead properly. It appears after a Headgasket replacement at a shop around 5 years ago (I have the reciept) the sealant for the upper half if the head was not perfectly applied and oil came out the unused port for the secondary air system. When i had the head open i did the hydraulic lifters (because ONE was bad) and the valve stem seals, aswell as the camshaft seals, because i was already in there, right? When i closed up the head i was too cheap to buy the proper tools (i know, shame on me) to make sure the timing was perfect, i just used the markings from shops who previously worked on it. By now i know it was roughly 0.8° (on the Crank) off, which i fixed last week. I also replaced the turbo cartrige, because it leaked oil on the compressor side and gave it new Injectors, because one was leaking.

When i got the 850 back on the road it ran perfectly fine, a bit rich, which didn't surprise me because of the new injectors (which i learned are probably not as compatible as advertised, the ECU hit it's limit trying to compensate). After a week, on a higher speed drive (around 200 km/h / 120mph, i am in Germany) it blew out a Camshaft seal though. I luckily got off the Autobahn just in time, but i lost upwards of 3 litres of oil somewhere along the way before the oil pressure light came on in corners. I stopped immediately and the engine seems not to have taken any permanent damage. Yes, the engine still has an oil level sensor, but it has no plug in the harness. Volvo decided not to use it anymore, because it proved very unrelyable.

After i got the car home i doublechecked the PCV System, it is around 10k km old. The pipes that i had cleaned but not replaced, now came new and i pushed a ziptie into the ports on the block and came up with fresh oil, barely any carbon buildup. I also checked the PTC heater and the Voltage supplying it, both work perfectly. I cleaned everything and figured the engine is worn, and thought if i don't drive that fast it will be fine, at least till graduation, then i will have time for it.
But nope, even when babying it, it blew the seals again, this time in city traffic (on the drive home from graduation :´). I noticed when i parked at home, again a bunch of oil lost, but stopped in time.

So then I figured a big revision, replacing the piston rings, was in order, because compression was low at 8 bar across all cylinders, but that was with the bad timing (I didn't have the opportunity to test again yet). To make sure a friend brought a leakdown tester and it was definetly leaking through the rings into the crankcase, not through the valves (which checks out), but we measured around 9-11% blowby across all cylinders, which was in the green. I had the opportunity to ask professional Mechanics (of 30+ years experience) and they say that this is nothing (especially for 350k on the clock) and not to worry about it. Upwards of 20-23% would be more what they would have expected from a worn engine, at 10% they said the rings were perfectly fine. I figured the turbocharger makes pressure aswell, so out it went and i put air from a compressor through it. Nothing. I also checked the Ports and Oil lines to the turbo and stuck an endoscope into every part of the engine i could reach. It all looked clear and cleaner than i had imagined.

So now, after a couple weeks reading Forums and the official Service Publications from Volvo, the only thing i found is that for early T-5s the small vacuum line that runs to the PTC Valve used to be a bigger diameter. I used the one from a kit, which is made for later models that have the port on the left of the intake, which i don't have. I have the early variation going to the vacuum tree, the metal pipe on the head evidently got lost sometime in the last 30 years, so the small pipe was extended to the tree, i took the extension out and connected to the tree directly. I also found a slight vacuum leak where the tree should seal to the intake. Two 1mm O-Rings should take care of that. At this time i figure that when i go off throttle (and i like engine breaking, i do it a lot) the small tube just couldn't provide enough vacuum for the higher rpm still pumping air into the crankcase.

But i feel like a bigger tube and a slight vacuum leak just can't be everything. I am afraid to go back on the road, loose all my oil again and maybe not notice in time and nuke my engine.
Does anyone have any other ideas where the crankcase pressure could come from and what to do about it?
Does anyone know how much blowby is acceptable on these engines? I could only find compression numbers, but i was told those are unreliable and leakdown was the way to go...