Rekka did some great adaptor cups for this, I had some Prolite 1"ers and a Hoffman stem to put onto a Schwinn Jay Miron frame.
It sounds easy and convenient, till you've got to find some of the damn things.
Howsabout the reverse? Isn't there a specific set of bearings you can use to put your 1 1/8" forks into an Old School 1" frame?