ORIGINAL: AMB
Mr Cox looks identical to mine
Yes, I didn't see the step in your image and thought it was just a darker band from where the head would protrude down the cylinder of a constant bore. I can see now that our engines are the same, in terms of the bore.
The glow version has the regular design, a constant cylinder bore, with the head protruding down the bore. Here is the glow AAC engine;