I mentioned earlier that it should be possible to port Tapan Kaikki (http://sourceforge.net/projects/tapankaikki/
). I actually started working on it some time ago, but gave up in the middle of it (I took wrong approach to changing resolution and there were some bugs which prevented me from debugging). The actual game can be made to run in 320x240 without any downscaling, but I'm not sure if it would work full speed. On the other hand menus work in 640x480 and those would need a downscaler. The source code has some bugs which prevent it from compiling (those can be fixed) and some which cause it to crash randomly (for some reason I was unable to debug it). Also there were a few ASM commands in the source code. There was only a handful of them, they didn't seem to be in the main game code and they were only used in the release build (or was it debug build).
Obviously the game needs data files to run and those can be obtained from the precompiled version. However, most menu images need to be in PCX format instead of the EFP format. The conversion has to be done using a Windows (or maybe even DOS) command line application.
If the game would not work full speed on Dingoo, additional speed boost might be achieved by removing the pseudo 3D effect (I have no idea if it can be done using a compiler flag or if it requires tinkering in the code).
I'm currently being lazy, but I might try porting TK4 one more time some time later.