Thanks for the detailed response and the support.
The trouble is I think I am fine with "per char", because even though it is technically possible to have the same char in single colour mode and multi-colour mode, I do not currently do that.
All I am trying to do is find a way of configuring each char in the UI to either single colour mode or multi colour mode, and set the only configurable colour for that char. My game only had 4 levels, so storing 1k for screen and 1k for colour for each level was fine.
I have the original binary dump of the game and I have created a snapshot of it using VICE. But a game snapshot in memory from what I can see would never have this 256 byte L1 attributes block, it would have a dump of the screen memory and dumps of the colour ram.
So in summary, all I want to be able to do is configure on a character by character basis the colour mode, and be able to import the colour ram for the map.
Even if I manually created this 256 L1 attribute block manually, can I even import it? Can you explain the format of this area again in detail please? What is the Material nybble? The colour ram only needs a nybble to convey both the colour of the character (bits 2-0) and the type (bit 3).