I can tell you from experience you should not cut the spacer. I made new spacers for Wendy's bike as an experiment and once you decrease the pre-load too much the bike bottoms too easily. I'm with Doug in saying to buy the kit if you want to do it then do it right.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!