I thought it was the Mk VII that came without sights, or the dovetail for a sight.

I have a Mk VI, S/N very close to yours, with a rear sight in the dovetail. It is secured by an allen screw which can be loosened to adjust for windage.

If your Mk VI has a front sight, then I would think it came with a rear sight.

I saw some sights in the Kings Gun Works catalog that look like they might fit in the Detonics dovetail. The catalog didn't have dimensions but you could probably call them and ask.