Either the Hot Rails or the Cool Rails will match very well with a Custom at the bridge. It's just a matter of what you're looking for in a pickup. The Hot Rails will give you some of the nastiest shred metal leads you've ever heard from a neck pickup. The Cool Rails is a little more versatile and can do pretty much anything with the right amp driving it.
I like the Cool Rails the best out of Duncan's Rails series. It has strong output, but is still clean and snappy. Roll down the tone control, and it can evem do jazzy stuff well.