The KIM-1 driver has been updated to use clickable inputs and the emulation can now read back it's own written cassette images. I have not yet found any direct wav dumps of KIM-1 cassettes, so I have not been able to test those.
If you want to try the KIM-1 emulation be sure to start with the debugger enabled and manually step through one or two cycles before the artwork is displayed. This is a mame core issue.
The KIM-1 sysinfo page on the mess wiki have been updated with instructions on how to write to and read from tape.