I never did went back from 7 strings and am eagerly awaiting my 8 string. though i just like the idea of getting a low D up to the Open low E instead of having to detune or approach it from the 5th fret fifth string. it gives a good sense of movement. it's also good for some chord voicings that used to be frets apart, but are now just a string away.
it's also terribly satisfying to just chug on that low B. I try to use as much as i can out of it. though some people would be better off using a detuned 6 string :D
to answer on your question though... ask tim. i kinda had the same requests as you and he recommended black dog bridge and mule neck. the black dog bridge works really well for heavy tones with clarity, but that was in an ash guitar.. not mahogany. the mule, well, i think it famously famous for doing about anything. it's a wonderful neck pickup for these tubular sounding paf leads. Also, from what i've read around here, alot of people here (including myself at first) ordered a bkp expecting more distortion, but didn't get that. instead they got more clarity and note definition, which at first, makes the pickup a bit harder to play with.... but as a new convert (i got my pickups last year and played extensively with them over the year) i have to say this added clarity is very welcome and turned me into a better player.
The thing is, i think (someone correct me if i'm wrong) that BKP's different pickups are mainly different in their EQ settings and the amount of compression they'll give. the higher output they are, the more compressed they'll be, and then different magnet types and wire gauges will gives the EQ that each pickup is known to have. make of this what you will but when i see posts about people wanting more distortion from their Ceramic Warpig.... i begin to wonder if they're really listening to the same thing in their tone as alot of guys here are... it's about the clarity and the punch, how the pup drives a good amp. if you want more gain, just stick a booster in front of the guitar into your amp and there you have it. the BKP will still drive the point home with as much clarity as before... but with more, as the booster boosts your guitar. anyway.... i think you get my drift.
like i may have posted around here earlier, he pointed me to a riff raff set for my mahogany 8 string to get the same kind of tones that my 7 string does. but i'll have to say that 1) you need to slam the front end of your amp to achieve big nasty tones with a lower output pickup 2) greater dynamics will make it feel a bit harder to play but it's ultimately rewarding. i'll have to say i love pounding the shiteeeee out of my guitar to make the riffs feel heavier. a higher output pup wouldn't give me that feeling. Also, he pointed out to me that the longer scale will drive the pickup harder and that if i was happy with the output of the black dog, the riff raff would be a great match. (not exactly in those words, but that's what i got from him)
but all in all, ask Tim, and don't be afraid to ask more and more questions to him. you may think we're all pretty helpful here but Tim takes the cake. and he's ALWAYS right on the money, even when you may think he's not :D
whew... quite the wall of text. sorry. but i know i was happy when i got replies to my questions when i first started around here. time to return the favor.
