Edgar,
I am attaching a link to Precision Reloading so you may see a brass spacer bushing. I use these on 600 JRs to load shells that are 1/4 shorter than what the press is set up for. They have 12, 20, and .410 (1/2"). They don't yet make a 28. But I'm sure with your machinist ability or contacts you could make them for 28.
Since the first three stations on the MEC 9000 only deprime and resize the metal, prime and dump powder, then seat the wad and drop shot, I believe after that station at the crimp starter station you could pull the shell, put the spacer under it, and put it back in its slot to move on after starting the crimp to the next two stations until at the last one where the shell and spacer would be dumped into whatever container. This would require making three of them to follow the 2 1/2" shells until they are dumped then remove the spacer and use it for the next shell. A few more actions but it would work. These spacers hold tightly to the shell and fit precisely in the MECs slots.
https://www.precisionreloading.com/c...!l=MM&i=SB2014