If I was you I'd plan on picking up a new set even before you start the work. I've pulled the valve covers on 3 different SHO's ranging in miles from 130K, 125K, and 80K miles. All 3 had the valve cover gaskets tear in one way or another. Mostly in the spots where RTV was applied. I'm sure that in at least one case I could have just added a little more RTV and it would have been fine. But my in my opinion I would rather have it done right then have a major oil leak from them down the road. Plus if you have any oil leaks from the spark plug tube seals you can pick up the Fel-Pro set from Autozone and just replace both the valve cover seals and the spark plug tube seals at once and be done with it.