Maintain or restore your thoughts, please

[russophile]

I apologize. I am using an online translator. I have this panel. The lettering on top Iиc and Xc are not part of the original painting. They were added sometime later. In a restoration would you remove them? There are remnants of nails made of silver still embedded in the board, would you remove them? I need to stablize the painting of Christ but after that I am not sure about how far to take a restoration. Would the experts here suggest a complete restoration or something different? I hope this helps. Thank you.