Holy shit, TD! Good thing you ears were attuned to the sound of your engine, and you sensed that something was amiss. Some newbie thoughts:

1) It's an air-cooled engine, right, so you probably did not subject the engine to substantially higher operating temperatures during the low-oil period. That's a good thing.
2) What's the total oil capacity of your engine, and how does that compare with the 900ml you added? If it only holds 900ml, I'd be more worried than if it holds 1500ml, as this would mean it was not running completely dry.
3) I'm thinking the most vulnerable parts would be the main piston bearing, which bears the greatest load, and the clutch, which needs that oil bath to function properly.
4) It's now been several days since your post. What's happened since then? Are you riding it? Any further trauma or abnormal behaviors? Have you had it checked?

Please do post updates, as this is something that could happen to any of us!

Also, glad you weren't hurt in your encounter with the bicyclist.

Good luck.