https://www.digikey.com/en/products/detail/infineon-technologies/IPA95R1K2P7XKSA1/9491055 looks like 500+ in stock.
I'd use anything 600V or higher, super high current not needed, 5 - 6 A or so OK, which means lower gate charge and gate capacitance. The model used in the simulation is similar, but now obsolete.
I made a search on Digikey, and got ~ 175 suitable candidates.
https://www.digikey.com/short/fp8qvz25
I'd choose fully insulated case to have one less thing to mess with.
The "317" normally does not need a heatsink, but I'd place on a chassis (with insulation kit) anyway, in case of an oops.
A steel chassis can be doubled up with a good piece of 1.5mm, or so, aluminum sheet, to improve heat transfer, and avoid added objects sticking out, but a personal taste thing. Finned heatsinks inside a box not so effective.
The circuit in the sim above lacks a current limiter, but as I found out, my chassis mounted PSU resistors, FET and 317, handled the a short nicely. I'm sure a rectifier tube would have fried.