Four months on and the project has mostly come to a halt.
I have the tuners, string retainers and neck bolts but no neck yet. Life keeps getting in the way!
Nonetheless, the project has evolved in my head. I am going to opt for an ebony fingerboard; my rosewood fingerboard on my fretless conversion (another project that has stalled) is already showing signs of wear from only light use. Whilst the wood is likely of relatively poor quality, I'll still cover by bases and go for ebony as it is, if talk is true, harder.
What will likely happen now is that I'll order a neck which will go on my Jazz. The neck on there now will go on a P body to become my fretted workhorse. Warmoth don't do an old school P body for five strings, so this will need arranging too.