I know 15.9-1 has been sucessfully done in a 654ci hemi on E-85. Joel I wouldn't be a bit afraid to try 12.5-13.5-1.
E-85 is rated at 105 octane but has different burn characteristics than gasoline. You also get the cooling effect than alcohol provides. When I ran it in my 440 right after startup, often times my intake manifold would be sweating. Operating temps were about 15-20 degrees cooler than on gasoline. Dave