I hope I'm not fracturing any rules by making this post but I am the person who makes the adapter kits mentioned by 1985 CCX and w.lewis. I m not a company but merely an individual who loves Cobras and had the resources available to be able to produce this item for other Cobra guys. I won't turn this into a commercial but I would be happy to answer any questions personally or via the link below.
The pentroof covers offered by PAW are a very nice item for the money. They do give the essence of originality but, of course, cannot display "Cobra 427" without stepping on toes. For those individuals who want the real thing, then the adapter kit is the way to go. Either way, the engine looks much better.
Below is a photo of my 351W with the adapters, original chromed pentroofs and a couple of other 427FE goodies that were adapted to the 351W.