I'm not saying this is what you should do, but it's what I would do.
Step #1 - determine if the rim is a true circle centered on the dimple I can see in the middle of the face. (Dividers make it easy, but there are lots of ways to do it.)
Step #2 - determine if the tenon that the chuck is gripping is centered - does the rim/face wobble when the lathe runs? Is the dimple in the middle of the face the center of rotation?
If the existing tenon is way off center, I'd remake it. I'd start by putting the entire block between a spur center and a live center (not in a chuck) to get things running as true as possible at the face rim, then cut the tenon again. (Yes, there might be some depth sacrificed, c'est la vie.)
Once it's good, I'd just pretend that groove isn't there. It's a bowl blank - chuck it, shape the outside, sand the outside, hollow the inside, sand it, and either finish it & part off or part off & finish it.