I personally dont have the MQ but the P90's i have used turned to musch when opening the gain above a dirty blues tone. Best overdriven neck sound ive gotten are from the '57 Gibson Classic (alnico 2) pickup, the Stormy Mondays sound very stable also with alot of gain. The classics i have now in my '73 SG also give that singing tube sound in the overdiven highs.
I dont know if you have this, but in the 2007 marshall catalogue there is a DVD with demos of the new product line, in the new Kerry King amp demo there is this guy playing with a gibson custom with our own BKP Nailbombs, he also plays a few chords on the neck PU and they really sound supertight and chunky, no mush whatsoever. If you do have the chance to pick this catalogue up, it would be nice to check it out.
I dont want to discourage you, but in one of the chambered LP's it will be even harder to get a neck pickup that really stands out, LP's allready have a disadvantage at a clear neck tone IMO and the chambered ones sound beautyfull but tightness (woodwise) is not their strongest point IMVHO.
Maybe a bridge splitable pickup would be an option.
Good luck, i am very interested what you will find out since i also would like to get more use out of my neck position.
Greetings, Henk