The (-) input has been decoupled by the capacitor. So the series resistance of the PD is not the matter.
In this sense, we should use 0Ohm for the (+) input shunting.
51 Ohm for CLC409
The datasheet of CLC409 uses 25Ohm there. This is to cancel the input bias current of the two inputs of the opamp.
The source impedance (series) of SGD444 is 50Ohm. So I used 50Ohm for the + input shunting.
However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.