OK,
I'll start this by saying that I've been ON a B40, but not sailed her. So I cannot speak for her actual sailing characteristics. But some observations.
First, the ability to make any passage is much more about the skipper/crew, and less about the boat. a guy a few miles from me crossed the Atlantic in a 10 foot homemade boat, so anything is possible. The B40 is CE-A rated, blue water for sure, but is clearly designed as a coastal cruiser. For my eye, the biggest differences between that and a blue water boat are storage/tankage, and seaway comfort. The B40 is huge downstairs, and looks like a Soho loft. But lots of open spaces without handholds, and the 6'10 headroom makes using the rooftop for balance hard. The large beds will have you rolling all over the place. A true seagoing boat would have much more storage, and the decrease of (human usable) interior space would allow you to wedge into areas to prevent being tossed. Even the head is huge. Al that space is great sitting at anchor entertaining friends, but after for 4 days tossed in a gale it would be a shambles.
The cockpit is also a party zone, large and open, with little bracing area.
The desk stepped mast might give some pause.
You say you want to cross the Atlantic.... then what? Turn around and sail home? Sell the boat? Cruise Europe? If planning to sell remember that if you have made mods and have created a blue water B40, and that's not what most users will be looking for.
Not trying to dissuade you... Hell I want to go... just think it all through!