It looks as if your experiment to adapt a Winchester 23 buttstock to a Fausti had a happy and successful ending. With the vast number of different frame and stock inletting configurations, the odds are really stacked against a project like this working well and coming out looking good. Congratulations. The proof will be in the shooting, and I hope it continues to perform well.
I'd hang on to the original straight grip stock because it will make the gun more marketable should you ever decide to sell it.