Maybe I’m missing something here. Indy, B-1, were able to develop and build a head without print specs from Chrysler.

But they couldn’t copy the bolt hole location for the valve covers? Or they had prints to do the head but no specs provided for the valve cover attachments?

My money is on the fact that the heads requiring unique valve cover attaching locations were purposely done so they could sell their own valve covers.

When it doesn’t make sense - follow the money.