I've updated the original post with my second round of testing. BMCM was correct in that the finish is best replicated with a WAO/GB blend. More specifically, 1 part White Aluminum Oxide 220grit mixed with 10 parts #13 glass beads (5tsp of WAO to 1cup #13GB) run at a lower pressure 60psi.

I may test passivating the 5906 frame with citric acid, but I'll need to do a little more research into temperatures, time, solution ratios, etc.