I'll change the inverter in my 60 the next days. Usually, there's not to much to worry about specification of the inverter, because it's no AKAI specific hardware.
Usually, the EL-foils work over a wide range of feed voltage. In case of the 60 the specs are around:
As TSR said, any inverter for illuminating EL foil will work as they are somewhat generic.
However, you will be hard pressed to find an inverted that is pin-compatible with the original Nichia one -- meaning it won't fit on the existing inverter board.
So you will have to use a protoboard or find some other way to mount it inside your MPC.