Try a .033 tone cap, which you can get rather inexpensively in an orange drop. It is, of course, between the .022 guitar cap and the traditional .047 bass cap. It will let more upper mids through without getting "squeaky," and will let more of the inherent grind that this particular pickup is known for shine with 500kohm pots when you roll off the tone.
As far as caps: capacitance is capacitance. For a typical passive bass guitar circuit, the type of capacitor has no effect on tone, whether mylar, ceramic, tantalum, poly, etc. What is important is using a capacitor from a company that has a good reputation for consistency and durability (no drift in value over time, like paper-and-oil will do when the oil dries away) so that when you purchase a cap of a particular value, you know you are getting that value, not 20+% out of spec, which will affect the tone. Sprague has been a standard manufacturer of capacitors for decades, and is known for their consistency and reliability. So their caps are good. I use them because they make the "in-between" values, like a .033 to retain more mids in a bass tone circuit, or a .0068 for a Jaguar guitar "choke" switch, etc., for a reasonable price. If you want a traditional value, like .022 for guitar, or .047 or .1 for bass, you might as well save the trouble and go to the nearest Radio Shack for $1.49. That's what I've done for decades for the standard values.
The only reason that I would ever pay a premium for a capacitor is if I was restoring a vintage instrument, and because of the particular nature of the instrument and its collector's value at a sale, I need the particular OEM capacitor to retain value and realize a better sale price.
