240Z: Sand blasting vs glass bead blasting (Transmission back)

Last week i brought my transmission housing parts and some smaller bits to the local blasting company. The guy made a serious appearance and explained how Aluminum parts like these normally will be treated with class-triangles to break-up old paint and remove it. and then treated with glass-beads (pearls) to increase the surface density. He even told me  he’s gonna paint the cast-iron parts with a clearcoat to prevent it from rust…
This is how it looked before:

Clearly old silver paint peeling off is visible:

Today i picked it up. and the first thing i noticed how “raw” and rough everything looked. It reminded me of sandblasted items. Sand-blasting is corrosive and will remove small spots in the surface of aluminum (like the transmission part) and give it a rough feel.
While the aluminum is thick enough to handle it, it just doesn’t look as smooth as a factory-fresh unpainted transmission should look in my opinion:

But since i don’t have a lot of experience, i returned home. What made me even more curious was the fact that sand came out of various spots of the transmission. Its clearly not glass-bead, nor is it any other glassy. I guess this is the “sand” they use for sand-blasting..
The guy even told me how hard it was to remove the paint from the previous owner. so i guess they switched to sand at some point.

While i’m all fine with that, i guess they didn’t glass-bead blast if after that. Somehow it gets a bit more shiny / glossy after glassbead-treatment and this sure looks like just sandblasted to me.

Also the cast-iron small pieces didn’t get the promised clearcoat…

Not sure yet. Don’t want to blamy anybody and it would clearly do the job. but i want to have it perfect. Either i bring it back or i bring it to another company to have it checked and re-done… have to think about it.
Or maybe it’s just me and the “gloss” will come back once it’s slightly corroded? not sure…