> about 90mA/V
OK, 100 ohms, 11 ohms, same within an order-of-magnitude.
Actually, I totally screwed-up. I saw the 82R5 and lept to a conclusion. Yeah, it is something like K170BL's GM. And I missed the X3 factor. I didn't fool with the X2 and /2 factors, though they do seem to cancel out.
So taking Gm of one JFET as 1/33Ω gives your result and seems plausible for the 170.
> For all I know, it's DEEPLY flawed in some way
It has way too many costly single-source parts.
The ratings may be insufficient.
No DC stability at all.
Otherwise, it seems to do the job.
> Mr. Thegard relied, maybe rightly so, on the transcendental equation for determining the mirror ratio with a single emitter resistor in the left hand transistor.
For 2:1 ratio you want 20mV offset; so for 3:1 you need around 28mV offset... ah, but at what current? Your Q01-Q04 current is ill-defined. Your resistors hold a 3:1 mirror ratio over a wider range of current. I don't know which of Norm's plans you looked at, but he may have used actual known-current sources.