I don't think you'll have a problem with a regular pickup as long as the string spacing is fairly aligned over the pick up magnets. If you'll be using the same bridge saddles, and just cutting extra slots for the octave strings, should be OK. If the action is too close like that, you might consider one of the blade pick ups that folks like Seymore Duncan, Bill Lawrence, and Dimarzio make. You'll probably need to revamp or change the saddles as well.
My $.002