Eddy RPM heads: Should I be concerned about this casting defect?

Send it back. that material missing in the half-round for the rocker support is unacceptable. It will not support the rocker shaft properly, especially on an end. The half-round is to support the rocker shaft from side to side movement, and most of it is missing in the one side. Now think how much it can move when you have valve spring pressure on it and revving it up.

If the machine operator for that operation didn't catch this defect, then the final unloader should have seen it when he unloaded and packed the head for shipping. It's called "final inspection". The guy who unloads the part from the machine line is supposed to do a visual check for defects on all parts. Period!

You paid too much money for that head to accept that bullsh!t. Return it.