Fitting the neck

Using the soldering iron to fit the inserts.

I have no doubt that there are specific requirements for how these things are put in properly.
The amount of heat required and its duration are probably also set in stone somewhere but all you really need is some patience. 

I left the screws in the nut inserts while heating but in hindsight I wonder if that was a good idea as it didn't really help that much to keep thing straight and distributed the heat a little too much.
Whether or not it makes a difference I don't know just some thoughts for anyone else following in my foot steps.

 Fitting the neck with the screws required that I applied some more heat while screwing in the screws
simultaneously to get them all to line up so they went in straight and without effort.

 I added an extra washer so the ends of the screws so they didn't go past the inserts as I want the flat part of the neck to be free of anything that will interfere with the fretboard when I glue it on and when the screws are finally tightened up after the fretboard is glued in place.

Trying to show you just how straight the neck is at this point but focus and depth of field are a bitch :-)

Settled on a straight edge to demonstrate the necks flatness.

All fitted and tight front.

All fitted and tight back.

The next step will be to trim the fretboard down to the correct length.
So I'm test fitting with a spare nut I had laying about.
This will help me get the scale length of 431mm as I have to trim the fretboard down so the distance of the nut and centre of the first fret are at the correct distance apart, which is 24.190 mm

I need to do some thinking about this nut. I need to check the string spacing and its overall width and test this nut against some on my other instruments before I move ahead.

I'll be removing the neck and after I've cut the fretboard down but before I glue on the nut with a drop or two of super glue, I'll use some small pins inserted into the neck that press into the fretboard so I can locate the same position anytime I need and then clamp the fretboard and neck down on a sheet of glass I have so the thing hopefully gets glued on as flat as possible.