The stock valve cover I have sits on top of the rockers. Rail spacers may work. Thanks Olds bro!I've seen roller rockers under stock covers plenty of times. If you insist on more clearance, you could do 3/8 rail spacers.
But, the cast aluminum ones are nice looking, too.3/8 VALVE COVER SPACERS BILLET 6061 ALUMINUM OLDS
3/8 VALVE COVER SPACERS BILLET 6061 ALUMINUM OLDSshop.rocketracingshop.com