I may be misunderstanding your question, but there appears to be no option for setting the encoding of non-Unicode encoded files. The Default encoding option actually says, "Default encoding for open files (used when auto-detection fails)" and my experience is that Linux/Unix systems are quite good at figuring out file types from the file content, which I assume is what auto-detection refers to.
I'm not sure I'm asking for Unicode to be used in this "ASCII" table. However, when I double-click on the 0x85 value, a horizontal ellipsis character ("…") appears. The underlying hex codes inserted are 0xE280A6. This is exactly the behavior I want. I just would like that ellipsis character to be displayed in the so-call ASCII table.
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.