I think theres a bit of a 10% leeway, I'm not sure 500 words will make that much difference.
I'm also guessing that they won't *count* your words, but as they are marking many many PIPs they are going to have a general idea of how many words you have.
That being said im 700 over and I don't give a shit.
500 words wont make that much of a difference.
My teacher is a HSC marker and she reckons as long as your within the word limit by 1000 its totally fine.
As others have said, the markers won't check..they have too many other things to worry about.
Having said that..dont go crazy...if you stick with what you've got you should be fine.