I'd argue for a PATB-1b Original Parallel Axis. It is a lot like a hotter Custom 5 with extended harmonics, sweeter treble and more even EQ. But if you drop the pickup height too low, it emphasizes the treble and bass, and gets weird piano/tele tones. Also kills sustain and midrange, though... But done to a lesser degree, might do just what you want.
Magnet swaps are a cheaper place to start, though. The flat mids and punchy bass of the ceramic and A8 versions [they mainly differ in upper mids through presence, with the A8 having a more vintagy rounded high end and the ceramic having a more biting presence, though not as harsh as most other ceramic pickups] might work, even though they have a bit more mids than the Custom 5. The added bass punch of either magnet, and the higher output, seem like exactly what you are looking for.
A boost or overdrive is also a great option. A lot of guitarists have bought into guitar amp marketing nonsense, and forgotten that the vast majority of recorded distorted tones involve some sort of added gain, compression, if not outright distortion or fuzz.