I actually built this circuit today and the measured gain was around X70, here it is a little higher at X84. The current source was made with a J113 jfet and a 100R resistor. If you require a higher input impedance I have a Darlington buffer circuit that can be used at the input.
Update 20-6-17: Have increased the power supply to 24 volts and adjusted the bias conditions accordingly, the voltage gain is now over 100.
