Yes that's better I can see what it is doing now. As I said before the 2N4125 is a general purpose PNP transistor so I suspect the BC558B would probably do. It is only in the output audio stage.
As to the FETs, what this is doing is a voltage controlled filter, however the filter sections are only first order and you have in effect a variable resistance from pin 3 of the op amp to signal ground. The matching ensures that the cut off frequency of each stage changes by the same amount. So what you want to match is the on resistance against the gate voltage. I assume that circuit in the other thread is supposed to measure that some how but it is not completely obvious how you use it.
I would just set up a circuit with a pot on the gate (ends to each rail) source to ground and drain through a 20K resistor to +ve.
Then plot a graph for each FET of pot position / gate voltage against voltage on the drain. You only need about four or five points on each graph. Then match up the four FETs that have the closest curves.
Best of luck.