You can modify the baffles around the
oil filler tube and the pcv valve to get roller rockers to fit, that's usually the only bad interference. Also you can get some extra thick valve cover gaskets to raise up the cover slightly, felcro makes some really thick cork gaskets, I think they are FelPro #1645. Just a little extra bit of height is needed, at least that is my experience with crane gold race roller rocker arms on 289 HiPo engines.
Z