I'm not an expert on fonts because my work doesn't require big fonts. I have looked at both the font files you attached and converted them to readable form. As you might see in the attached image, the ISO3098.shx is an incomplete ASCII font file. The ISO3098B.shx is a complete ASCII font file. If you only need a diagonal dash through the 0, then that font could be modified easily using the developers guide instructions. I imagine though, that Norwegian has many unique characters that are only accessible with Unicode, not ASCII code. Those letters must come from a big font file, not necessarily bigfont.shx.
Look at the support files locations for AutoCAD stations that work well. You can't just look at the standard font folders included with AutoCAD. You must look at a drawing that works, look in the styles command, copy the names of the regular and big font files and do a search, in AutoCAD using something like (findfile "iso3098B.shx").
The example above, assumes that the iso3098B.shx is used in the style that appears correct. That will tell you which folder to copy from to make the new stations work correctly. IMO, each office should have a folder named fonts, somewhere that is not locked down by AutoCAD where you can add and manage fonts. This folder should be added to the support folders in AutoCAD. You must find the big font that has the appearance you are looking for and add that to your new installation's support file paths.
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