If that were my buck, I promise you I wouldn't be telling my buddies I killed an 8pt.
If you wanted to decribe it well and have people being able to visualize it, you should call it a "busted up 8-pointer". You can specify that it's an 8-pointer with the ends of the main beams broken off.
If you call it a 6-point, I would picture a forkie with brow tines.
You would have to do more describing to get the full visual if you started with 6-pointer than if you were honest and called it a broken 8-pointer.