Jeff,
Check out the latest editions of Pagoda Notes (available on the tech manual section) for a listing of the changes and when they occurred. All the big changes for the 250 SL came at VIN ending 2980, mid-year through 1967 to comply with the DOT mandates.
For your car the headlights should be "AC" you can see the letters molded into the plastic. These were not changed until early into the 280 SL run.
The tech manual also has a listing of the headlight covers, what they looked like and when they were changed.
The hubcaps should be separate trim rings and "dog dish" style covers over the center of the wheel. These carried over into the first few of the 280 SL.