That would be awesome!
I wonder if Tarantino is going to cast a ‘not A-list’ guy though for Manson since the role will have a potentially career damaging effect. I would go with Michael Angarano. His performance in Stanford Prison Experiment showed he could pull off a Manson. (That whole ensemble cast was so good. Ezra Miller is an intriguing Manson choice too but he kind of already did the serial killer thing in We Need to Talk About Kevin.)
Anyway, it’ll be interesting to see who he casts. To this day, I still don’t know whether Jeremy Renner ever played a role better than his portrayal of Jeffrey Dahmer.