A quick note, because I'm a bit stupid and hadn't tried that before...
When the hinting doesn't look very good for a font, instead of exporting it to TrueType, and autohint & autoinstr, you can also try exporting (or not, if it's already a PS font) it to OpenType CFF, clearing hints & AutoHint seems to give far more nicer results
. [Read FontForge's docs, you may need to tweak a few settings in the preferences for autohinting to work correctly].
In short: Prefer OpenType CFF fonts over TrueType fonts when targetting a K3
And autohint ftw!