IF....you can see fit to expend the bucks, look into having the iron manifolds ceramic coated. I had mine done by "JetHot" - and used the aluminum finish, but it is also available in a cast iron gray. Not only does it look very sharp - but it can cut your "under-hood' temperatures immediately. At the time, they cost $225 and were back in a week. They may be able to put the heat funneling aluminum surface on the inside and gray on the outside - dunno.
Not a cheap fix - but I finally just saved the beer money for a few weeks and bit the bullet. My wife and the Doc were happy - so was the 'Bird.
Steve Metzger Tucson, Arizona