You can take a caliper and compare what's left to what the service manual believes would be "within spec". I don't see why you couldn't re-use it, just break in gently over 500 miles.

But as everyone else suggested, don't cut costs and just install a new one. I understand reusing one if it has 5000km, but if it has anything over 30,000km, just go with new.

 

Thanks for all the help guys! I got it all installed and the car runs better then it ever has!