I'm not claiming to be good in any way and maybe these numbers are completely crazy btw, I just wanted to share my ideas. Also, the PBE was made for testing purposes, so it wouldn't be that bad to just test some increased numbers.
Furthermore, there might not be a need to do all these buffs all at once, maybe 1 or 2 would suffice.
Passive: take out the AP ratio, why is it even in there ? otherwise idk what to do with her passive other than maybe buff the base dmg to the same as kha'zix's (and lower the AD ratio)
Q: 85 / 110 / 135 / 160 / 185 (+ 100% bonus AD)
W: 10 / 17 / 25 / 32 / 40 (+ 20% bonus AD) (out with the AP) (I have no idea how to balance increased auto dmg, my brain can't math that much)
5 / 6.25 / 7.5 / 8.75 / 10% (<- change something about these too ?)
E: To be honest, it's perfect as it is.
R: 130 / 190 / 250 (+ 160-165-170% bonus AD) (+ 10 / 12 / 14% of target's maximum health <- these max HP rations seem fine but maybe they would bring forward a better solution to her lack of dmg)