The ABRSM's Selected Keyboard Works, Bk.1 or II might be handy, the first collection features the Harmonious Blacksmith, but mostly comprises items that are grade 3 or 4, and some that may be easier. I don't have the second book, but since it's got the Fantasia (grade 6/7) I suppose it would be a little more taxing. Would recommend the first as a solid and immensely enjoyable collection
http://www.abrsmpublishing.com/publications/1739As for the grade of the Harmonious Blacksmith...depends how fast you go. But I think you could expect someone around grade 6/7 to have a go at it steadily and produce a pleasing result.