I can't say that Ive seen "holes" in a cast iron manifold besides cracks, (I guess that's sort of a long "hole") but I too am gonna be fighting a driver side exhaust manifold on a 4.7 once the weather gets better, I recently bought the Lisle drill template kit last week because I found a deal on one/ most are around $125 that I've seen, I got mine for 1/3 of that...
Hopefully the job goes such that I end up not needing to use it. ..
But id rather have one on hand and not need it then to try and find it/wait for it to be shipped etc with the thing already torn apart.
I've wondered about the headers for this application myself but been scared away from them by the ridiculous pricing I've seen on them.