I would say my son would be:
Maths NC Level 7+
English Level 4 (his creative writing is only passable, while his comprehension is weaker, but his spelling, punctuation, etc. is pretty much 100%)
VR around the 135 range (definitely not up to the 140 level)
Also his EP report provided a LOT of info, and showed that his maths ability is in fact exceptional rather than merely very good.
In terms of prep, for me the EP report was well worth the money, since he obviously has an uneven spread of abilities, which was fully explored in the report. Apart from that, VR practice: get this book www.galorepark.co.uk/product/parents/704/how-to-do-verbal-reasoning-a-step-by-step-guide.html and go through each type of questions in turn, talking about strategies for solving (e.g., eliminating answers that could not be correct, to make a guess more likely to succeed), and then practice VR papers (Bond or similar) until he is getting 90%+.
The VR stuff is very easy to coach and make big improvements, so definitely worth doing.
There is always a 1/2 hour comprehension and 1/2 hour creative writing session, and I did lots of practice with past papers from other independent schools (Manchester Grammar has lots on their website, and should be of a similar level). I didn't seem to make much impact on the comprehension, it was still awful, but perhaps we did. The creative writing seemed to be easier to coach, because there are more rules - beginning, middle and end, make sure you practise writing within a half-an-hour time frame (no point in trying to write a massive story that would take 3 hours to complete), plan a few points before starting.
When discussing with the school SENCO she/we did wonder whether the schools would be interested in him on the basis of his exceptional abilities, or reject him on the basis of his worst areas (the lowest score in the EP report was 10 (verbal comprehension), which is exactly the 50th percentile, so he's not that bad - level 4 English is average, nationally, but obviously not usual for the intake of the most selective schools) risking the precious 90% A*/A at GCSE. The fear was that they would reject him, but it does appear not, thankfully.