Re: Pickup suggestions ?
I stand by what I said about the tone of a JB split and would put it up against any other coil in the list mentioned so far. The P-90 coil of a P-Rail will also do a great job; though I am not impressed with the sound of the the rail-half of the pickup, especially in the bridge position (YMMV).
That said, I would definitely not recommend a JB in a single-humbucker guitar. While shrill is not how I'd describe the JB, it is not what you want to play Zeppelin.
What I mentioned was a JB/Custom hybrid with an Alnico 2 (or possibly RCUOA5) magnet, which you would need to either make yourself or have someone make for you. What I should have also mentioned was that it was only a musing on my part. I've not heard one, but I'm betting it would be a pretty versatile pickup. You will get very useful tones splitting (or better yet: partial splitting) to either of the two coils (better than the coils of either the 59/Custom or the P-Rails, as a pair, IMO) and it may easily sound really good in parallel...for Zeppelin. I do plan on making one in the near future.
With that aside, the 59/Custom Hybrid and P-Rails are both very good choices and I would not argue against either.