....
Any ideas on the best way to do this? I have access to a Rong Fu
Mill-Drill.

If this were plain carbon steel, I'd probably use an end mill to "drill"
the hole on a new center. But I'm not sure how well that will work with
316 stainless.

Right idea. Wrong machine. I've never used one of these Rong Fus so I don't
know for certain, but I don't see how they would be anywhere near rigid
enough. Be sure and use a low speed and a high feed when you do this. You
don't want to workharden the cut.

You'll want a few spare endmills. Personally, I'd use 2 flute HSS here. But
others may disagree.

Karl