Follow this link and you will see one of these heads for yourself,it was made from 351 cleveland heads,it would be a pretty expensive head to build.
There are also crossflow heads for the 300 that are made by ford in australia,you can buy one and have it shipped over.
Check out my photos as well,you can see my latest 300.(the green one)
The 300 is a great motor,mine is pushing 300 hp and gets great reviews at all the local shows just because it's different.