And what exactly does castlevania sound like?
Adding a in a bit of organ, and maybe some Baroque and fugue styles wouldn't hurt. It doesn't even have to be as forceful as other CV games(where music is blasting you down). I always pictured a really atmospheric CV where you can hear an organ being played, but it's almost if someone is playing it in a distant room and it's echoing within the halls. "Ghostly music", not sounding "spooky", but music that is like a chilling whisper, adding to the ambience, not overpowering the situation with it's presence, but still there nonetheless.
One situation I thought up is, what if you were exploring an area and Bloody Tears was being played on piano, a gentle roll. Apparent it's there, but so soft, it could be the wind. I want to see some CV music to that effect.
Oddly enough, being developed and composed by folks from Spain, you'd think they'd go for some of that spooky Catholic church musical sound with organ pieces and monks chanting hymns.