Some pictures.
Bellhousing - Yes I used an automatic case to demonstrate the uneven finish (tone) across a main case for an example. The upper left shows how bright and even look blasting often recreates even though, in this example, the guy didn't finis. The lower right shows what appears to be one that has been blasted then painted with aluminum paint Chances are is that the restored example is painted or ceramic coated with a very thin coat
Cast transmission case and tail shaft housing
The upper left is an example of a nice original. Does appear to have a little surface rust in a few areas but does show a tonal value I believe you will find is in the range your looking for. Typically don't save or post pictures from restoration in these sort of threads but I think the one in the lower right shows the contrast between the top cover and the main transmission cast sections. The filler plug IMHO is brighter than I have seen on originals
Hoe this helps