I think so, yes.
The good news is that the WJ tests use a mathematical model that you can plug the scores into and then extrapolate based on age/grade that is entered.
When DD was tested we got two outputs AE (age equivalent) and GE (grade equivalent). It ought to be a simple matter to get the tester to rerun the numbers using a different grade.
I am no expert on testing but i do know this from first hand experience - we got this done to support the case for our DD's skip from 2nd to 4th. We were able to get the numbers produced as though she was entering 4th grade ( tested mid way through 2nd) based on her raw scores. So it works 'forwards' and I would expect it to work 'backwards' too.
Good luck.
