There's a type of resistor that's made exactly for applications like yours (pulsed, low inductance, high power): Metal film resistors in transistor packages.

Here's an example of a 20W type that can take extreme pulses such as the one you expect to dissipate in the resistors: https://www.vishay.com/docs/50005/rto20.pdf

Depending on the actual voltage you expect to encounter, you could put 10 to 20 of them in series, giving you a total voltage rating of 5kV to 10kV and a power handling capability of 200W to 400W. The momentary overload capability of this resistor string would approach 100kW for 10µs, according to the datasheet. (Each resistor can handle 20W continuously, >5kW in 10µs pulses, and 500 Volts)

Keep in mind that you have to cool the resistors appropriately. Additionally, if the voltage spikes exceed 2kV, you have to put insulating pads between the resistors and the heatsinks to avoid dielectric breakdown of the resistor's package. Alternatively, you can tie the heatsinks to one leg of each resistor (or group of resistors) to lower the voltage between the resistor and heatsink. Note that this puts the heatsinks at high voltage.