I never did do an HPI on mine, but due to various things, I suspect mine had a Cat C worthy crash in its lifetime...
It rides fine, handles fine, and it a custom end can short of perfect. End of the line, no matter its past history, it's yours now. I have an annoying habit of buying abused bikes, and losing a fortune of each, but then again. My current Fazer now has a caring owner (despite the occasional thrash), and is perfect for me. I know it's gutting when you find flaws in your perfect machine, but sadly, flaws (things going wrong) are inevitable. It's how you live with them.
I know I'm not saying anything new, but look at it this way: Your bike had a prang 14 YEARS ago, has been on the road since (and presumably relatively extensively to boot), and is now owned by someone who will take care of it. I personally would advise the following: Forget the HPI, and ride it for 3 months. When those 3 months are up, if you still feel you want to sell it, then do. Just don't be in a hurry to cut your nose off to spite your face.