How to create a load dump test setup using two power supplies?

Question

I have a Keysight N5771A which goes up to 300V but the response time is not fast enough to be used for the load dump test. So I use it to supply the 202V and another power supply to supply the 24V. Here is the circuit:

^{simulate this circuit – Schematic created using CircuitLab}

1. Does this circuit work? I do not want to blow up the lab and the Keysight PSU (rental equipment).
2. What do you suggest to use for the diode and switch?
3. Is it ok to build this circuit just using flying wires or it need to be fixed? Can I use a breadboard?