No, you don't cut the seal- - - -shorten the top of the valve guide so the seal sits lower on the guide and the valve has more room to move up and down. I've had to do that on lots of guides when I went to the positive style seal instead of the O ring on the valve stem. I always check that dimension when setting up a set of HI-PO heads.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!