In defense of the CGB, the Game Boy Color is really a different device. It's a more powerful computer with a few more capabilities, so if you're using it for your project, it should be because you want to use it specifically. Game Boys aren't expensive enough, even modified, to create a situation where you have to choose one over the other forever.

Also, the GBA runs pretty much exactly like a color, so you can always use a GBA SP for tracking or whatever extended use activity you'd like, and then just use a Color (pro-sound or not) to record.

Using a GBA SP would be way better if it had a headphone jack. Also, the cgb loads songs way faster and has more battery life, but the sound is different too.

Also, the GBA runs pretty much exactly like a color, so you can always use a GBA SP for tracking or whatever extended use activity you'd like, and then just use a Color (pro-sound or not) to record.

That said, this is a pretty involved mod and probably isn't well suited for a beginner. Proceed at your own risk.

The most common method is to use the frontlight out of a broken AGS-001 Game Boy Advance SP.

If you can't find a broken one, or don't want to gut a GBA SP at all, maybe you could find an Afterburner kit for the original Game Boy Advance.

That said, I don't know where to get those anymore, and I haven't done this mod before, but maybe that information can help you.