I'm going to discard that pot as its so hard to get anything out of it.
Once I'd got it out of there is discovered that the roots were 6 foot long and had been doing laps of the pot. This type of root is very different from other species i had worked with before - and it was extremely pot bound. Interesting that the root growth had been as vigorous as the above ground growth which had been rather extreme during the peak of the growing season last year.
Any of the new acorns ( 12 being prepared now ) that germinate this year will immediately go into larger pots based on this knowledge.
I lack experience with repotting roots like this - so I decided to be cautious and not cut back the large long roots too much. The placement in the pot was defined by getting the large root system into the pot and unwinding them. this may be a mistake - we will see what it looks like when i repot it again in a few years.
The pot is a little to large - but I'm aiming at massive growth over the next 2 years so i need plenty of headroom.
The soil is filtered Akadama and fuji grit ( 70 / 30 aprox ). I'm hoping the fuji grit stops it setting like concrete. The good akadama is cheaper than local hydroponic alternatives and is very effective. So why not ?
The cat was very interested in the process and lent a hand as usual.