Ideas? On a drill jig for converting Magnum heads to LA intake

Now I have a plan for the new year where I am going to use an old stock keg style Magnum intake and an old 318 TBI intake and make a drilling jig out of that. I'll chop and mill away on them till I just have the flange left. My first thought is to drill the ends of the Magnum flange for the LA bolts. Once you get the end holes drilled you can bolt the LA flange on there to locate the rest of the holes. I know the stock holes won't be perfect so I'll have some figuring there but that's the start of my plan anyway!

Cley