The physicality of the reconstruction alone would require impossibly good casting. A leg that's actually injured, a body with epigenetics consistent with the inferred diets of ancient Egyptian monarchs, food preferences consistent with dental wear marks... and so on. That leaves aside finding someone with the right physicality who can even act, and learn Egyptian, and so on and so forth. Which still leaves aside that there would be a lot in the actor that was not in Tut. Jim Carrey was not Andy Kaufman.