The ESP Guitar Company

I'd also like to know. Old post, but I just emailed support this morning to ask, since the information hasn't been easy to find, and with the model discontinued, it's pretty much comes down to a guess if the KH-602 has the same size nut (43mm)

Hey Gary,

I'm sure you figured it out on your own by now, but for anyone else looking, got a response:

Unfortunately, ESP does not have records of instruments from older time periods.
This model should have a 42mm nut width which would use an R2 style nut.
The Floyd Rose bridge and parts that were used on this model are unfortunately no longer produced so any aftermarket Floyd Rose parts may require modifications to be done to the instrument.
If you have any further questions or concerns, please feel free to contact us.

I'll be attempting to use the R2, and will confirm here when I'm done.

As promised, here's the update: the R2 nut does fit, however it's visually imperfect. Doesn't seem to affect the playability or spacing of the strings at all, it is just a tiny bit shorter than the original. I would recommend going for an R3 - I'll probably be doing the same next time I can get my hands on one.