I've written a song that's based largely around G major, with some C major parts. However, the G major progression utilizes a B7 chord, so it sits outside a normal G major scale.
I've heard lots of songs take the vi chord and turn it into a 7 as well.
I'm wondering how to approach writing leads over this or improvising over it. Is there a scale that typically fits well with this? Or should I just spend time figuring out how to adapt a the G major scale when the B7 hits, so I slide some of the? fingers down a half step?