I'll put in here my usual reminder of if you can do methods well, you should certainly consider doing specialist. As for the options you've suggested... It doesn't sound like you really want to do any of them at all, and rather you're just looking for the lesser of those evils. Do *not* pick up an extra VCE subject just for the sake of extra score, actually pick up one you think you can enjoy and do well in.
In terms of music, which music? If it's music investigation, your dislike of theory may or may not be an issue, because all theory you study will be theory that defines the music you're playing, and you might actually find it enjoyable. If it's music performance, then the theory you'll be doing in VCE is nothing next to AMEB grade 6 theory. If it's styles, then... I can't really comment, sorry. For the performance aspect in investigation/performance, you might struggle - unfortunately, there's no real mix between AMEB and VCE for the practical aspect, and I've seen high scoring AMEB students get study scores under 30. This can depend on the instrument you choose to perform with, so be wary if you do pick music.