As with any JFET in this configuration, it'll likely need to be tweaked depending on the parameters of your specific JFET.
That's much easier with a trim pot.
According to Benson all three JFET drains should be biased to 4.0VDC, I've updated the documentation to reflect this. It's worth noting that Q1 has been measured at around 5.0V on multiple originals, so as always, tweaking by ear will likely be necessary