It looks better than new to me, too. With some items, such as vintage cars, I don't care for "over-restoration". However a twin-rail SB45 is not a rare art-object, and you haven't changed the concept, you've just done the job SB tried to do in the first place, and done it better. (If you'd done the same thing to a single-deck SB45 I'd be a bit uneasy though. However it's your mower, and your decision.)