Here's the disassembled inner lock face.
I removed the facade of the dead bolt and milled a relief to accept the servo neatly.
I had to ream the screw holes a little deeper to clear the bottom of the servo. I drilled and tapped the bolt holes.
I'm using a tiny piece of acrylic I slotted and screwed to a servo arm to twist the linkage.
The lock is now ready to install back into the door. I'm not sure if I'll make a motor cover or leave the servo bare.