I was told that on the single coil routes on the Model 5fx's, the pickup leads came out of the underside of the pickup and down a channel on the treble side. The channel was not drilled from the center of the single route and then into the humbucker route as on some makers' models. At the time, one could find Duncans-a-plenty where the lead wire cam out of the underside on the treble end, and so were direct replacements for Jackson's pickups.
These days, however, they're all tailor-made for the Fender Strat S-S-S style route - the lead comes out of the center of the rear edge of the pickup (not the underside), even if the pickup casing itself doesn't have the old-fashioned Strat-style tabbed baseplate, the wire is still coming out of the same spot, which makes them essentially useless in these older Charvels and Jacksons. But oh, feel free to hack yourself a notch into the pickup cavity so they'll work.
As for the bridge, you'll need an oversized pickup ring, which can be found on Ebay or at a site called fretsonthenet. Dave there specializes in making oversized old-skool Charvel/Jackson pickup rings.
Which pickup you put in it is entirely up to you. Try several different pickup combos and find one that works for you (though as I said, finding a Duncan to replace the single-coil will give you issues).