I put a Rally cage on a Nuovo Record, but it didn't shift too well. I tried a double sprung Rally on a short, horizontal Campy racing style dropout with a modern freewheel, and it shifted great. The combination shown here works well too:
http://www.flickr.com/
The Spence modified Record looks like it has a Simplex top pulley (Rigidex or 303 Tourist perhaps) and a Cyclo bottom pulley. I once had a Gran Sport that was modded with Rigidex cage. It wasn't by Spence, but the Desiree guy in Santa Barbara whose name I've forgotten.
Leonard Bulger
Marblhead, MA USA