Well, I have been to an engineshop. The mechanic told me that it would be best to replace the liners, pistons and rings with a new set. Later on the accountmanager of the shop asked me what the mechanic told me. So I asked in return what it approx. would cost if I order a new set. Well, he didn't looked at the engine but he was sure no new parts are available and if they would do an engine revision it would cost me €3.500 euros. I was adviced to look for a new engine.
I said I would give it some thoughts and thanked them for the checking the engine parts.
...
Back in my car I had a good laugh, €3.500 euros!? Bwahahahahahaha!!

So I will order a new set on Franzose, as well with new bearings.
Next monday I have an appoinment with another engineshop. I noticed some (very small) scratches on the crankshaft. Probably they can polish the crankshaft. So I'm curious on what they say!
In the meantime I had a guick look on the stearingmechanism, man, it feels like it has been very worn out on the inside.. Can't wait to disassemble it..