My 5 year old Kindergartner is having similar issues, but I can't even have him "officially" tested until 3rd grade (they keep telling me.) I will have to look into this Wechsler testing you mention and am mad that I waited this long to try to test him privately. We are in Richmond, VA.
His reading test in October was at a 98% level and they are still making him learn letters he knew before he was 2 years of age. Trying to move him itno 1st grade - but suffering with behavioral issues as well. Can't tell if they are totally relatd to boredom, and slow to develop because he is also clever in other areas, or whether there is something else wrong.
Hope to find out some more information from other parents as this is my first visit. At least your son is reading the time line. My son keeps getting in trouble and wants to play (only child). He does well with one on one attention at home and gets really invovled in puzzles and 1st and 2nd grade math.
My son also not thrilled with the handwriting thing - I don't think boys like that as much as girls keeping in mind my own experience and not wishing to sound sexist.
I'm sure that if we test our son he would score lower in some areas, espeically regarding the acting out.