I would find out if the school would even look at outside IQ results. I don't know where you are in PA, but around us (SE portion of PA), a lot of districts will not accept outside testing, and many won't test until around 2nd/3rd grade.
If the school doesn't clearly state the policy on IQ tests, ask other parents. If they don't accept outside testing then there might not be much use in testing (unless he likes tests and you want to see the result).
You should also investigate what the gifted program is like in elementary. Many programs are weak for the younger kids. We had the school test the older two in 7th grade to gain entrance to a special course in HS, but there wasn't much worthwhile prior to 9th grade in our district.
And perhaps you might not even need the testing. With our middle kid, teachers in 6th grade sent her to the gifted pullout even though she was not officially in the program. The gifted support teacher put me on the gifted email list. The admin folks didn't think she would qualify (FSIQ > 130), but the teachers saw something in her that the admin folks did not. It seems that his teacher recognizes that he is bright and wants to help with placement for next year - that is a start.
