Hi Bees-

The old SBLM goes over 160, but that's very rarely used these days. Check out this hoagies table for how different tests compare.

http://www.hoagiesgifted.org/wisc_vs_sb_l-m.htm

Has your son had achievement testing? A Woodcock-Johnson type ach test might give you and the teachers a better idea of exactly what your son has mastered and what grade level he is operating on in various subject areas. This information is more concrete and specific and may be more useful in advocacy situations.

It's ridiculous to say that only a PG kid can benefit from acceleration. Most PG kids are multiple years ahead of age/grade level across the board. A one year skip won't do much to challenge a kid who is 3+ years ahead, will it? A highly gifted kid might be "only" 2 years ahead in every subject, does that mean she won't benefit from a skip?

Have you seen the Templeton report on acceleration? Check it out here:
http://www.nationdeceived.org/

You might want to browse the site and acquaint your school officials with it as well.

best wishes-