Edit...I take that back. If that pic was taken how you found everything there is a chance that with the bushing being destroyed on the drive gear that it has cause the driven gear to "walk" toward the driver side of the car causing some issues. Still wouldn't explain the interference between driven sprocket and 4th clutch hub.
As far as the bushing that goes between the drive gear and channel plate I am going to have to stick with installation error. Did you even find remnants of the bushing? was is ever put in the trans? Without it, it's going to cause damage just like you have pictured.
Additional Edit....Where is the drive sprocket retainer clip that holds the sprocket in place on the input shaft?
