First of all, the most important question which you must answer before I can really offer my assistance is what kind of guitar is this going in?
as well as what kind of wood is it made of? what wood for fretboard?
played acoustically how is the guitars natural eq? (example: bright, dark, honky, balanced)
I wouldn't recommend the pearly gates for that type of tone. You are on the right track with looking at vintage output humbuckers, but something with a smoother tone would suit you better for that sound. Again depending on your guitar the Alnico 2 Pro should be perfect for that sound, or also the Jazz. In any case I wouldn't suggest mixing the two, although they are similar in that they are both smoother rounder sounding pickups, they achieve that in opposite ways.
The Alnico 2 Pro; like the name suggests, uses an Alnico 2 magnet, meaning spongier lows, strong mids, and rolled off highs. This in combination with the low resistance of the pickup makes it a darker pickup with a softer attack, often attributed to a singing quality, though not vocal sounding like Dimarzios at all. It is smooth because of the lack of high frequencies.
The Jazz, has an Alnico 5 magnet, meaning the bass is tight and deep, the mid frequencies are slightly scooped and the highs are extremely clear. This pickup works well both clean and under hi-grain sustaining solos because it will remain clear. One thing to remember is that a higher output pickup is not necessarily better for hi-gain, it is only designed to achieve higher gain than is possible in a more vintage amp, boost the mid frequencies, and compress the signal. The jazz would suit your needs perfectly so long as your guitar is not overly bright, because the last thing I want to do is hear you complaining on here in two weeks about how you put two jazz pickups into an h-h tele and played through a bright amp. It is not so much smooth as it is chimey, more like a single coil though still distinctly a humbucker sound.
Tell us more about your set up and we'll be able to be of more help. What specifically is it you'd like the change about your current pickups sound? What kind of amp do you have?
EDIT: Also check the seymourduncan forum, use the search function and you should find tons of helpful hints on this exact subject. the people on that forum are the most knowledgable I've ever found, just be sure to use the search because they don't like answering the same questions over and over again.
