Door Lock Cylinder replacement

[beechboy90]

I do not have a key for the current door locks on my 66 Chevy C-10. Thus the question... Is it easier to grind the tumblers to match the ignition key as it fits into the lock, but wont turn it, or if you buy new door lock cylinders, How are you able to pop out the old cylinders? is there a trick?
I am grateful for any ideas on what has worked for others in the past.