Re: I love the '59 neck but lows are too flabby and bassy
Lower bass side, raise screw poles to compensate for volume is first thing to try to drop bass and maintain string balance.
Also, shorter polepiece screws under the wound strings gives a bit more attack and rolled off low end, too. There's also a trick of shunting the bass out with a high pass filter, search for Artie's De-Mud Mod.
If those don't do it, magnet swaps are up next. A3 will drop the pickup's volume considerably, and will give a squishier feel, but yes, much less bass. Sort of a brighter, quieter A2. A4 has a bit less highs and lows, but stronger mids. Replacing A5 with A4 doesn't have a large impact on output.
A4 is a classic PAF magnet, along with roughcast A5 (a bit smoother treble than currently more common polished A5) and A2.