How to choose right capacitors and resistors for installing Ground Lift Switch in ReAmp Box?

[MOnk332]

Hi,
I'm trying to build DIY Reamp box recently, and I stumbled upon some circuits without Ground Lift Switch.
Transistor in that picture has 600Ω : 600Ω impedance.

On the other hand, the famous Jensen AS092 has 51Ω resistor and 10mF capacitor.

So, why are they needed to be installed in the first place, and how should I calculate and choose right parts for the each circuits?

Thanks.