Hi Ads,great news,
my main concern is that distance nut to 12th fret will be roughly half the scale length to the bridge saddles so it will be able to be intonated. Sure they have enough brains to check that it will work.
Should be ok to leave the nut width 42mm. I'd recommend dot markers so they can be changed to block marker if the builder wants to do that.
I think tuner holes might as well be drilled like a standard paddle. You really need a drill press to do that properly which may be out of reach of alot of builders.
Keep up the good work Ads !