What is he reading on his own? If he is reading chapter books independently, then you can get a ball park figure of what that level would be by googling "title book AR level". That should give you a grade level equivalency.
My ydd was also on the just below mark for WPPSI as well, we applied with portfolio and were asked for more information. We'll do achievement testing for her later on. We think it will be better to wait until she has taken off more with both math and reading. She is leaping ahead right now, but we'll wait more....
