Thank you for your detailed info. we must check the 4v mark on head.
I have to buy what is available will be answer. I understand the difficulty to find the parts that has proper casting date. We living in japan has more difficulty to do so than others like you. It may be impossible. Just what we can do is to make mangusta rebuilt to near original condition within what we can do. I understand the rebuilding cylinder head is an option. I don't know what is wrong in head. Maybe there is few special technicians for ford small block in this area, so I guess that importing the head will be cheaper than rebuilding. Tomorrow I will visit my friend and talk about these issue.
thanks for very useful info!