As was sort of mentioned earlier, while the Apple // and TurboGrafx share an extremely similar CPU, the graphical and audio hardware is not even close. The Turbo is lightyears beyond everything up through the Apple //c+ graphically. Even if you had the Apple // source code to a bunch of games, you'd probably have to rewrite most of the shit anyway. At the very least you'd have to create all new pixel art.
how are we going to get the source for an apple ][ game? lol
break into MECC and steal the oregon trail archives?
If it was made in basic, then its not a problem although I doubt it was.
The point of porting an Apple // game was the assumed similarity of the architecture, thus (theoretically) minimizing recoding requirements.
If the game in question was written in BASIC, then the former point is rendered moot since BASIC is BASIC and is platform (CPU) independent.