I use to plug my M-II UC through a Screamer head. However, I prefer the EMG 85-85 rather than the 81-81 combo. I also have a M-II NTB loaded with Blackouts: I like the sound of the bridge pickup, but just the neck pickup did not impressed me. Play thrash metal, BTW.
As for passive pickups go, you could try a Wilde L500XL / SD '59 combo.