So youd have to mess with the casing on the Super CD System to get it to fit?
it should fit. in the video on the thread in neo geo, it shows working on a tg16. its the connector that would interfere with it not fitting. the slot where it goes in on a TG16 is smaller. other than that, the dimensions on the back of the console are the same.
here is an example of ten no koe 2. if you remove the extra plastic (circled in red) from the connector, it fits fine on a tg16
the hole lines up perfectly with the ac adapter plug
they said they were going to test it soon to make sure though, but i dont see why it wouldn't fit.
the issue with the pinout being different on the exp port is just when you a modding one. this is due to the pcb being upside down in shell. it being on the opposite side of the board makes the pins you need to solder to different from the normal pinout posted all over for the pc engine.