If you prefer the tapped sound then you like low wind single coils with a bar magnet and got the wrong guitar. But I think a good set of PAF or filtertron style style buckers that are more in the single coil range of output would totally change your tune. Your guitar would probably play well with a pair of Lollar's Lollartron pickups that are Gretsch style in a Gibson case/mounting. Either that or maybe go Neil Young and put a firebird pickup at the bridge and put something P90ish at the neck like a Fralin P92. But I digress. If I were wiring our guitar I would put a phase switch in place of the coil tap to avoid the gaping hole. You could repurpose the existing switch for the job and it will work with a 2 conductor pickup.
1) Gibson and Fender determined the values for their pickups. Even Gibson single coils always got 500k whereas Fender used 250k until the 70s when they started experimenting a bit with really high values like 1meg. The higher the value the more treble it passes when wide open. A 250K pot loads the treble more than a 500K. Fender pickups are inherently brighter than Gibsons because of the magnet placement so Leo went low to smooth the top a bit. A lot of modern Gibsons and Gibson style guitars have 300K. Gibson experimented with lower values on certain guitars values in the 70s and gauged down to 300k some time in the 80s or 90s just to split the difference. Recently Gibson has started using 500k againin some of their nonhistoric models, but not consistently. Some of my Gibsons came with 500k and some 300k or 350k. No rhyme or reason at all. Its a mystery. A lot of far east sub-contractors build both Gibson and Fnder styled guitars so they only use 300k pots in their guitars to split the difference between the 2 camps and save on costs. Some old Japanese guitars have really wonky pot values, others are historically accurate in every detail right down to the Sprague caps! As a rule an LP style guitar with alnico humbuckers of low to medium output will sound most right to the most people with 500k pots across the board but YMMV.
2) Your guitar may have anything from 250k to 1meg, who can say?! Even if Hagstrom specced for one type of pot there is no guarantee the factory they contracted in Indonesia slavishly followed Hagstrom's instructions.Buying pots without markings helps these subcontractors to fool the big guitar companies who hire them by keeping their parts cost way down. Its just cheaper to buy 10 million 300k pots than 5 million 250k and 5 million 500k.... but I promise you that the pots are not of stellar quality. I tend to like CTS and Bourns pots though the feel is different on both when adjusting. I can tolerate Alphas but I have definitely broken them before, they do make a lot of good options in switching pots though at a VERY good price compared to CTS. Bourns just started doing high quality push-pulls but I've not tried them. I have CTS in most of my guitars, Alpha push-push pots in my strat and I tried the bourns pots in my SG if I recall. All these guitars sound better than stock and the controls are easier to adjust accurately while playing. In my opinion CTS upcharge heavily for the name and the look (they were Fender's vintage pot of choice and they still make the vintage model that looks the part in a fender cavity for sticklers... my esquire came with 250k CTS "dish" pots and if I replaced all the caps with some PIO or tropical fish type ones it would look vintage inside, but who cares). You could also experiement with a lower bridge value and higher neck to better balance the treble response of your 2 pickups. 300 to 500K bridge and 750 k or 1meg neck? I have been considering doing a 1meg on the neck pickup of my silver Les Paul to make the neck chimier and more usable for non-jazz playing... its a good sounding pickup, but once I have an amp setup for a good bridge crunch tone using the hot and bright Duncan Hybrid in the bridge the Burstbucker at the neck sounds a bit dull and boom thru those settings.... I digress
don't buy the Warmoth pots, they are not so hot. Better than what you have but not the best taper and a stiff throw when turning them quickly while performing. I tend to order my parts from Mauser in bulk (which is why I have spare Bourns pots sitting arund, Mauser stopped carrying CTS if I recall). Or if I am not buying just to keep my stock up I will purchase the exact parts I need for a project from a guitar only vendor with the stuff I want. For switching pots and such I tend to look at GFS as they have great deals on Alpha pots and little toggled and sliders. I have also dealt with Specialty Guitar and Mojotone.
Feel free to ask more questions about the magical world of guitar guts. I took the day off today and have no specific plans (I actually might do some soldering later, heh... I am thinking of modding my fuzzface for more treble and clearer bass, the Hendrix sound is okay, but mushy with Gibsons)
here's a wiring scheme I think will be ideal for your guitar if you are dead set on keeping the stock pickups:
http://www.skguitar.com/SKGS/sk/Images/diagrams/CoilSel_phase.jpg
different push/pull combinations control which coil you have active and you can flip the phase on one of the pickups regardless of which coil(s) are active, so you have access to every possible tone but neck and bridge in series and humbucker in parallel.
I can't find a good wiring diagram for 2 standard 1 way coil taps, 2 phases and a master parallel/series switch so I will have to draw you one if you are interested. That will get you every tone known to man but parallel wired humbucking which is highly overrated though it produces a REALLY pronounced strat-type quack if you are into that.