Honestly my favorite 7-string pickups for not-the-chugs is the Pegasus/Sentient set from Duncan - really even voicing, balanced, not too much of any frequency, and the right blend of clarity and glue to the notes that makes the low B mesh well with the rest of them. If you're going Blaze Custom in the bridge, I'd probably do either the PAF7 for something more classic or the Ionizer 7 for something a bit more modern and sparkly.