Congratulations on getting a nice Les Paul.
I would go for a Mule in the neck. No matter what, get a Mule in the neck. The sound is amazing and is just what the majority of Les Paul Players are looking for. As far as the bridge goes, this is more open to your playing style. You can't go wrong with a Mule in the bridge.
I think the stock pickups in a Les Paul Classic are 496R and 500T ceramic high-output (neck at least 8K, bridge at least 15K). The bridge pickup is a ceramic. Ask yourself if you like the basic tone and output level of the bridge pickup. If you do, then consider getting a BKP ceramic humbucker that is suited for the for the Les Paul. For instance, consider a Cold Sweat. This has a slightly lower output than the 496r (13k) and is an awesome pickup. If you like the 496t you also might be oriented towards playing more modern rock or metal and the Cold Sweat can cover this in spades.
If you like the overall sound of the 496 but you want to stay away from Ceramics (but you still want a rockin set of 'pups") consider the Crawlers. These are also awesome in Les Pauls. I also like the Rebel Yell for modern/hard classic era rock in a Les Paul. I tell folks to get the Crawler for the vintage vibe or the Rebel Yells if you want a more modern sound. Both pickups are outstanding Les Paul Pickups for moving beyond the vintage sound. You may or may not have to throw out what I said about getting a mule neck pickup with these higher output pickups. I am fine with it, you absolutely get the best of both worlds if thats what you want. Just to confuse you further, my favorite combo is a mule neck and VHII bridge. Pure magic as the VHII is so creamy, yet articulate and so responsive. Its slightly lower output. It can deliver the goods but it's still well matched with a mule neck.
Back to the basics. If you want a classic Les Paul sound you can't go wrong with the Mules. These are going to be lower output than the 'pups in your classic now but your fingers and subtleness are going to be much more important in your playing. Despite all the different kinds of pickups, through the right rig, a Mule can do just about do anything. Look at all the different types of music recorded with 59 Les Pauls. If you want to go a little hotter in the bridge then get a Mule neck and a Black Dog bridge. I think this is the classic 59 LP sound, or a version of it (ala Jimmy Page).
I always tell first time BKP buyers that the cardinal feature or characteristic of a truly good pickup is that is can be versatile. This is simply because the pickup has a good tone and broad frequency response. BKP have this in spades. Almost any set of 'Knuckles in the ballpark of your playing style is going to bring you a lot of joy and you'll never change them out of that guitar.
Unless your really in the know about a specific tone you want (and that's why so many BKP models) then take it simple with a set of Mules or Rebel Yells, Nailbombs, Crawlers, or the ceramic Cold Sweats. That way, if your not sure, just match the output or style you like. From there you can consider mixing and matching; that's a lot of fun.
I just love BKP pickups. Best pickups ever made period.
jms
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