My DC's school seem to provide their levels differently, but do state the maximum is an 8. The levels she was given last month were as follows:
English 6.75, Maths 6.75, Science 6.75, Fine Art 5.75, Ethics 7.5, French 6.5, Geography 6.75, History 5.75, IT 6.25, Music 5.25, Spanish 5.25, DT 5.75.
The other comparisons clearly given above are higher than my DCs so not sure what's normal. However, she's been told her Ethics level is the highest in the year (240 pupils). A recent practice controlled assessment in French gave her an A*. From what's been said to her, and then us at options evening, the school would anticipate she'll be sitting the higher GCSE papers rather than foundation where only a C is available, so they must anticipate she could be capable of a B (or hopefully the odd A).
Obviously I don't know what levels your son has, but hopefully the above helps a little. My DC is in all the top sets at a highly thought of comprehensive school by the way, so there must be many other DCs there and at other schools with lower levels