EB - AU V8 heads will all bolt on, not just the XR8 heads.
I'm running ED XR8 heads on my '67. They are commonly known as E7's.
AU2 - AU3 XR8 heads would require special headers/extractors due to the spark plug angle. From memory, they are referred to as GT40P's
Only Alloy versions I'm aware of were on the T series cars. Aftermarket, there are quite a few options.