One important thing about the kits is that they predominate over the boardset, so specifying D2K is more important than specifying TKG-x.
What I mean by that is, if you're using a D2K or HS kit, it doesn't matter what boardset you're using because the kit is actually running the game code that's stored on the single EPROM chip on the kit, bypassing whatever ROMs are installed on the PCB. The kit uses the rest of the PCB hardware (RAM, sound chip, etc.), but not the ROMs.
That means you could have a TKG-3 with Japanese version ROMs, but if there's a D2K kit installed, it will play the US code.
Do with that info as you will!