The goal is to drive a 47k load that requires at least 5mA of current. The design is as shown, with FET values matching their part number:
An LTSpice simulation (with generic pmos and nmos devices) demonstares that ideally the circuit should behave as follows when V1 is cycled from 0V to 8V:
Currently the voltage across the resistor remains at 300V even when the input is 0V. I've exchanged the pmos and it keeps the node at 0V but does not respond to a 5V input from V1.
I'm unsure as to what values R1 and R2 should have, originally they were both 100kOhm, or if there is something damaging the pmos that I have not considered. I haven't worked with such high voltages before and originally this circuit was designed for 5V (with R1=1k and R2=10k).