Kukeiha Club absolutely MUST compose the soundtrack to this movie if it's going to have the Castlevania feel. They are the original composers to the games soundtrack and I don't think there is anyone in hollywood who could do better.
http://en.wikipedia.org/wiki/Kukeiha_Club
Bra m Stokers Dracula was good, but people going to see this movie aren't going to see a "vampire" movie, as there are plenty of vampire movies. And we aren't interested in seeing an "action" movie, or any standard movie.
This is a video game movie. The most important thing they need to do is capture the FEELing of Castlevania. And having the original composers compose the soundtrack would certainly help in capturing the feel, but the whip also absolutely must be the main weapon.
I don't remember a sword being a weapon in Castlevania. I remember the whips, I remember the music, I remember the feeling of it all and it was not a typical vampire game.