I have finalized my project with some minor inclusions. The biggest change is that I decided to follow the H2 v2 schematics published by Nelson Pass on diyaudio as an alternative setup. This uses the cheap and available J113 jfet instead of the 2SK170. And uses a potentiometer in series with the loading resistor to provide gain adjustment.
The schematic still depicts values for the original jBoZ design. But I also include an LTspice model to help find a functional point for J113.
This gives around 12x gain. The issue is that the potentiometer will probably become scratchy after a while because of the DC running through it.
I also added the option to allow users load the jfet with a 10H at 600R choke, boosting gain to around 200x or 23dB
Hopefully I will receive the PCBs from Elecrow before the summer vacations.