I think you may be right about them being a AG mix, I still am unsure if they are bantam, I know the possible fathers that I saw were standards. And they look a lot like the pic you posted. Some have red necks and some a buff color neck, I think she had 4 or 5 roos. They were free range and came...
I have posted a couple of stories about these guys... long story short, they were malnourished when a friend gave them to me, they are aprox. 3mo. old and have taken a long time to mature. The roos on her property look like beautiful OEG they are just stunning. She has no idea what kind they are...