Maybe try the famous Liebestraum, it should be around the requested level.
I will never get the point of these threads. You know the level you want to tackle and you know the composers you want to play; why not just go on youtube/wikipedia, listen to their ouvre, and pick out a piece you like? If you are beyond the grade 8 then a good portion of their pieces are already accesible to you anyways.
In terms of playing I am grade 8 ABRSM level (if not higher). I am looking to learn a really flashy Chopin/Liszt piece, that at the same time is not exceptionally difficult - for example, not one of his ballades nor one of Liszt's etudes. What should I learn, and how long should it take to 'perfect' given say >40 minutes of practice per day. I am currently also learning Chopin's waltz in E minor Op.Posth.