Just give Ewan McGregor a gray beard and he should look similar to how he was drawn in Rebels.
I’d be prepared for a CGI Alec Guinness in the last scene though. I would love that.
CGI Alec Guinness is out walking and just as he tops the next hill, there he sees Luke, R2, and 3PO. He prepares to make the Krayt Dragon call…and cut. The End.