Reshaping abs?

I printed this part out of ABS on my bubbly bed, I’d managed to push the air bubbles out the way of the print area but as I’d let it finish whilst I was away the bed cooled and the bubbles came back twisting the bottom surface of the part. You can see how the top of the part in the picture is disfigured as the bubbles resurfaced underneath it and forced the plastic to twist (the top of the part was actually the bottom layer as it printed the other way round)

I need to try flatten this out if possible. I’ve got a new surface on the way if needs must but this is for someone else and don’t want to keep them waiting.

Cheers for any suggestions.