Regardless of what the intent of the stock design was, the barreled action looks to be untouched other than the magazine which can be easily sourced.
Take that barreled action out of this stock and have a correct Rigby styled stock made and you have yourself a suoerb 275 Rigby on an original Mauser square bridge!
Place this oddity stock in storage - nothing lost.
If this one hadn't been modified, it would be a $10K + rifle!