They should use Anthony Ingruber, He did a very convincing impersonation in The Age of Adaline
He has the voice and mannerisms perfect, and a strong facial resemblance.
They already cast someone named Alden Ehrenreich as Han Solo. He sort of looks like Harrison Ford.
To be honest, I’m a bit more fired up to see this Han Solo one and Rogue One than the actual saga films. I always dug those filthy bounty hunters and various other people Jabba called “his kind of scum” :-).
While I have to admit that I loved Episode VII, I can’t see them taking the story into any jaw dropping kind of scenario like they did in Empire Strikes Back. These stories like Rogue One and the Han Solo styles of ‘prequels’ can do all sorts of neat stuff (short of killing off Han or Chewbacca or Lando :-) ).