drilling magnum heads

You can't use the dual pattern manifold. It wants to start the bolt holes a little bit low. However I did find that the metal 318 intake gasket makes a great template.
Also if you have a broken bolt in a magnum bolt hole you can grind it flat and then drill the LA bolt hole. You don't need to remove the broken bolt.
I used a c-clamp to hold the fixture where the end bolt was broken.