Hi Steve,
I guess you're after covers like that found on a T3 Tickford 5.6 Windor?
Like anything Tickford, FPV or HSV, if they are available they'll be way overpriced. Eg a T3 plastic engine cover was $2000!!!! Plus you need a Tickford VIN for them to deal with you.....
You might have better luck using a wrinkle paint yourself.
Cheers
Al
Just re-read this thread and I think I've mis read what coves you actually want. One of mate's cobra has roller rockers and the covers you're after. I'll ask him and get back to you.