I would suggest you look for another NC 1.8 with a short MOT and buy it. Run the car to check it does not burn oil, then swap the engines. You can buy a donor car for around £1000.
Yes I would agree, if I was seeing that amount of oil usage on a road car i’d be investigating why it was, that amount means something is a bit wrong.
But then it does say under duress, so on track then it’s a different story, as you’re at high rpm for most of the time they do use a fair bit.