Sorry but you will have to do it again.
We need to see a photo of the radar gun to be official.
Police radar guns are calibrated several times a year, so using different guns in different parts of the country shouldn't be an issue.
I am really surprised the AMA doesn't have an event like this. Even if it started years ago with stop watches and progressed to radar or GPS. What would the AMA require to start an event like this? Would there have to be a SIG?
I wonder if the transponder system the R/C car racers use could be adapted some how?