That would be 30 mm less diameter, so what I'm thinking the rotor would be 15 mm lower on the pads.
That sound right ? Seems to me the calipers would have to agree.

2005 Model . Two Fast Eddy stickers , a bell and a clock . She's Lola . She tinkles and keeps time . http://s649.photobucket.com/albums/uu211/britbike05/