No casting call will be needed as David will play his father. I also don’t think there will be a wizard in present time because David’s father is suppose to be dead.
If they had an actor in mind, they may not have had a casting call. There was no casting call for the WWW or Gorham’s character.
But it would be cool if David’s father was the Wizard
Gorham is just Uncle Henry nothing more.
Here’s the one problem with this: the timeline.
The Oz story of the ruby slippers and Dorothy, according to 205, “The Doctor,” happened 10 years BEFORE the Original Curse. And then 28 more years passed while everyone was frozen. That’s 38 years.
The way they have styled and made up Gorham’s character, he is his natural age of about 35. For him to be Uncle Henry, he’d have to be much older looking.