That spacer being 8" would most likely mean +8 like Red said.

No matter what they are, if you're planning on going 6" shorter you either need more rake in your frame, cut the fork tubes, or get the right length forks. Cutting the spacer down 6" alone will NOT do what you're wanting, it'll just bottom out the front end. 

"Impossible is a word to be found only in the dictionary of fools." - Napoleon Bonaparte