Steve, the piston pictures are from this thread about my short stroke rebuild. There's a little more info on them in the thread.
https://www.accessnorton.com/NortonCommando/short-stroke-750-build.5160/#post-54374
Ken
Hi Steve, I posted a picture of the original Omega cast short stroke pistons that I started with on this page. Are they the same as the ones you have?
Ken