Is This 452 Head Ruined?

No it's not ruined. You can do a couple things here.. like... you can tap it , the lower portion, and run a stud on that stand by then drilling out the upper threads of the broken part , you will use a nut on that stand from there out.
That would fix it, but I would also braze it as well. You have to be carful if you drill it deeper, you may hit the water jacket.