Hi,
You can add in the translation override file the line:
G="Gr"
in order to have it displayed as Gr instead of g. The override can be accessed in the config under the tab languages when editing your translation file.
We'll add ozt for next release.
I'm not sure I understand what is a spin column. If you want, you can cheat by using another weight unit and use the translation system to display the price per column where in fact it uses KG or something else. As long as you don't need the weight for shipping methods restrictions, or that you don't need to do any unit conversions for it (you need to have that weight unit in first place in the config option so that it is the main one used and use it in shipping methods and products weight and no conversion will be done on it), you can use another unit and just change the translation.