I had a 28 and loved it. It was great for partridge, and patterned well beyond what you would expect for so small a bore. I sold it, of course! Later, built one for my wife. She still has it.
Long story short..I don't think that the 28 makes a great turkey gun. I use my 10, but would make do with a 20. If the 28 is all you've got, pattern it on paper before you take it hunting. Mine worked OK with up to 3/4 oz of #6 shot mixed with 71/2 . That was a heavy load.