So the car got totally repaired. These are the things I changed:
Gaskets + screws on the cylinder head.
Cylinderhead
Thermostat with the courtneys, the lower coolant temperature is nice (y)
Timing belt Tensioner (z20net), as this was ruined because of the water.
Cam chain guides, plastic guides got broken. They went into the oil pan(n) - I also picked them out of there one by one, took some time
Oil pump and cover, the pump and cover totally got ruined.
Water pump was all good (y)
I also had some issues with the oil not reaching up. Flushed the engine with some engine flush liquid, didn't work. So I flushed it with diesel. Lots and lots of dirt came out of it. While the engine was open and standing in its place, I also decided to remove the pre-cat. The extra bhp is definitely noticeable, somehow the acceleration is less on lpg than petrol now tough. Will have that checked later
Now its all good and running. There are some little amount of water residue left in the engine, gonna flush it out with some engine flush liquid very soon again.
Thank you all for your reply and help🙂