This is a sweet idea. I'm thinking once I need a new felt tire I will go with a 120. So ya just buy a rim and use your stock laces and hub? Use stock spacers? How wide of a fender would ya need to use?
Also that cross bone rear wheel is looking really nice on your train what bars are those your running?
They absolutely handle better. Now go much wider and yo start to get away from it's handling. A good way to judge performance and handling is to lookat what race bikes run. 120 front, 180 rear, which are ideal sizes for turning and agressive ridding.