Thanks FrankenWashie,
From research I've got the same measurements for the 1st fret as you. So my nut is a long way out making the guitar unplayable.
Yes, you're right, the nut is sitting at a bit of an angle. Especially on the high e side.
Looking at pics of the GR 1sf kit from the Pitbull website, my nut and it's position look a bit different, but it's hard to see.
The intonation seems fine.
My first thought is that I will need to file all string slots, if I've got to correct it.
I'm going to wait for any other comments.