If it has to be a physically based Ghost, please GF, give him Shadow Claw, or even create a new, better physical Ghost-type move and give to him. Ghost-type attacks have much, much better coverage than Steel-type attacks, and I personally would rather use Shadow Claw than Iron Head, unless if I had to use the latter for more power. If they really create a Ghost/Steel-type, I wish that they do it with stats like those that Heatran have. Heatran has good defenses, excellent power, and its speed isn't that bad. If that Ghost-Steel had Levitate, it would be an excellent partner to Heatran, protecting him from Fighting- and Ground-type attacks, while pairing the two with a Grass-type like Celebi would solve the problem with Electric- and Water-type attacks.