Using the starter is a risk. If this was a '82 Chevette then ok, but I wouldn't risk it on a handbuilt 280SEL 4.5. The last of the real good cars.

I doubt you are going to break the crank bolt. Unless you use a 3/4 inch impact on it. I would remove both valve covers and replace all of the plastic tubes that oil the cams, just to be safe. It wouldn't hurt to use some engine assembly grease on the cam lobes. I would drain the old oil out and change the filter also. Oil capacity is around 9 quarts. Pulling the plugs and soaking the cyls with a light oil is a good idea. I would also make sure that the rubber fuel lines below the air cleaner and leading to each injector are sound. Many a D-jet v-8 has caught fire because of fuel leaks here.