Classic/Antique Car Repair: Ignition Key Cylinder Removal for 1966 Mustang, key cylinder, door locks

Question
I believe I need to drill out the ignition key cylinder for the Mustang I bought so I can put in a new cylinder and key.  What is the best way to do that?  Or is there an alternative  way to remove it?

I tried to get a key cut using the door lock cylinder.  But the key that was made won't turn the ignition cylinder.  Not sure if the key was made wrong or the door lock doesn't match the ignition key.  I don't have the original key.  

Any other advice would be appreciated!

Thank you,,

Answer
First of all the door locks and ignition locks used a separate key in this era. I am not a fan of drilling out lock cylinders and I have a local locksmith that can make keys. If he can pick the lock to get it to turn you can then either get the cylinder out or make a key for it. I drill as a last resort because I always seam to screw up and drill off center.
Brad