I think that you have everything. The other dial like this that showed up (on EE27264) was an accumulating dial, with an extra ring/dial and a gear train that rotated the secondary ring so that you could read the inches of travel. (Very cool!) The empty holes in your base casting are for the gear train.
Here's a link to the accumulating apron feed dial post:
The post has a link to a website with more photos of the dial innards. (It's owner,
docswarf, hasn't posted here since 2013.)
But, the good news is that you have the only dial like that that's shown up here. A real collector's item! I don't think that even the world renown 10EE iron-hoarder, rke[pler, has managed to score either version of the dial.
By the way, you might want to mask off the machined surfaces when you're painting. Paint in the wrong places will cause you problems down the road.
Cal