The 11-28 cassette you are talking about (from Sheldon Brown, right?) is pretty good cassette for something of its kind, but why would you want the bigger gaps when a 12-27 with a 53T ring does a better job.

If you really want a 28T IRD makes a 12-28 9s http://www.interlocracing.com/cassettes_steel.html. Then you can keep the 53T ring and get what you want.