[NASSTY]

Steve,

My mate used the standard ribbed cover you're after (originally with a gt40 intake manifold). His has Ford Power on them but they were available woth cobra as well. To make them fit he had to do two things. On the inside of the cover there are casting "pins" that he machined off which the gave the clearance for the roller rockers and to fit the AU cover gasket, he machined of the lip/step around the base of the cover which fits over the head.

These covers weren't anything special to fit roller rockers he just modded them to suit.
Hope that helps

Al