Purchasing someone else's head and then advertising them as your companies modified cylinder head from that someone's else's company is OK. Edelbrock knows exactly what is going on and supports it. How do I know they support it? They still sell the head to Indy.
There is no fine line. This is just simple biz. And it bennifits both parties. The Edelbrock logo is on the head and Indy does modification work on it. I do not know if they put there logo on it to further state it is there modified Edelbrock head.