Like most iOne made board it use the 1.5,1,1.5,6,1.5,1,1,1.5 on bottom row. None of the other keys are non-standard. Easiest solution for keycaps is probably to source them from Cherry boards as those sizes are common on many models. Getting a winkeyless 1800 or similar for the 1.5 keys, and an 11900 for the 1x windows, menu and 6x space would be a way to go. Of course you are stuck with either black or white pretty much unless you get lucky and find some non standard colorway.
It's a lot of work for the BW in my opinion though. Personally I would just hock it on ebay and get rid of it and something better.