I went through this a while ago with a steel steerer (in 1 1/8"). At that time the star nuts provided by Chris King were a tight bfit in the larger ID steel steerer. The number of AL steerer star nuts were plenty and if one is using a star nut on a carbon steerer then you are in need for more then a well fitting nut...
But this thread speaks to the changing manor of our industry. back in the day one would just visit their LBS with steerer in hand and test fit the shop's stock. But this was when it was economical for a shop to stock all the various sizes of a common part. Of course in today's world of so many manufactures trying to stand out in the market place that the number of choices are bewildering to many and, IMO, needless in real life design. But it's not the after the sale service that so much of our distribution model is based on so no surprise. Andy