I have the 490/498 in there and I like them a lot, but want something that will push my jcm 800 a little more. I play in a hardcore band and need a good chunky palm muting sound, and with clarity for chording. What do you use?
For the bridge position try the PRS Dragon I Treble, very articulate for such a hot pickup (ceramic magnets and 18 kohms). For the neck, I recently tried a DiMarzio Air Norton in my PRS CE22 and it's quite hot but with good clarity and definition. I wanted something more PAFish so I replaced it with a Benedetto PAF but I think the Air Norton / Dragon I would be a killer combo for hardcore.
Got a Gibson Tony Iommi in my SG, and it works pretty well for me. Higher output than the stock 490T, and a sharper, crunchier sound. i play hardcore and metal as well (through a Dual Rectifier), and it's pretty much perfect for my purposes.
bareknuckle nailbomb. it's the best high output pickup i've ever heard. they have several other high output models that might suit you too. they're a bit spendy though. if you want something cheaper i'd have to recommend a duncan JB.
I'm thinking a jb would be too bright and trebly. The marshall especially is a bright amp so I was thinking that the custom (which is a bit less trebly and a bit more bassy and middy) would fit the bill.
The best I have tried in my LP Standard is the stock Burstbucker Pros if you want vintage with good bite, the WCR Goodwoods if you want fatter, bigger and smoother, WCR Shredder if you want thick and even sounding but it has a ton of output (keep that in mind), and the Rio Grande BBQ which is thick and full and medium output. All would be good but it depends on your ears.
A 300k volume pot works best in my LP for the bridge volume so keep that in mind when ordering the kit.
The Fillmore bridge was too bright in MY LP, but it may be fine in your LP. It works much better in my McCarty.
I really like the Goodwood because it will do vintage tones but can do high gain metal all tay if you ask.
The Duncan C-5 is also an awesome pickup of choice. A buddy of mine chose that over all the boutique stuff he tried. You never know. All of the above and recommendations of others are great but just starting points. You may like something different than any of us.