There's already a very good port of Gaplus done back in the day, not sure I could improve it dramatically. Got a number of potential projects on the go....not decided which to focus on yet.
Yes, Gaplus was ported to the Commodore 64 back in 1988/1989 and was released as a budget game by Mastertronic. I have the tape original which the start of this video features the loading bitmap and Rob Hubbard's awesome tape loading music.
This port of Gaplus to my general opinion is absolutely brilliant. The coders did a marvelous job porting the game to the much loved 8-bit computer.