New door locks for his 64 are not quite yet made of unobtainium but if you do find new they will be expensive ($200 plus!). I’d convert the locks to the easily found 66-up locks.
I took my 66-up door locks, my 65 rear power window key assembly and my ignition key (80 J Body) to an old timey locksmith who converted the door locks and power window assembly to the ignition key
