As experiments go, it was rather a long shot. The UV LEDs I’ve got emit UV light at a wavelength of around 400nm, and EPROMs need to be exposed to UV light at around 250nm. However UV is UV so it was worth a try.
It didn’t work :(
In the end, it had around five hours of exposure and after reading back the EPROM contents, not even one bit had changed state. Still, I suppose it’s nice to know.