Could Ned Stark Have Been King?

Ned couldn't have been the King on the Iron Throne no more than Rhaegar Targaryen could have been Lord of Winterfell.

Would Ned Stark have made a good king?

Ned would have been an awesome King. First thing he would have done is kill Cersei, The Hound and Littlefinger and Jaime, say goodbye to 90% of the corruption in King's Landing.

What if Ned took the Iron Throne?

Eddard likely would have named Jon Arryn as Hand of the King, and Stannis would take over as Lord Paramount of the Stormlands. He would have pardoned Barristan Selmy, and allowed him to remain on the Kingsguard.