How would you fix this?

[ozzbike]

I would look at custom making a cradle for a roller nut set up or a solid brass zero fret/nut/string guide combination.

you could also do an accent piece behind a standard F style nut, like a decorative plate behind the nut?

Frankie I could not help myself....I bought this one.....The nut will cause some issues...but man the rest of it is sweet.