What value cap(s) do you suggest I try?
In this situation, a smaller cap will cut more bass - the opposite of how it works in a tone control.
I'd probably start with .047uF, then try .033 or .022, or even smaller depending on how you like it.
I've never gone lower than .022 myself, but I wasn't looking for a really skinny sound.
Caps are inexpensive; it's worth getting a handful of different values.
You can get a hundred cheap ceramics in assorted useful values for a couple of dollars on Amazon or eBay.
100 assorted mylar chiclets are only about $10 (for a buck or two more you can 350).
https://www.amazon.com/Tnisesm-Metalized-Polyester-Capacitors-Assortment/dp/B08F52JC22?th=1
Unless you're a builder or repair tech, that's a lifetime supply of tone caps.
A subtler option is ArtieToo's "De-Mud" mod, which clears the lows gently without changing the overall sound much.
It's a cap and resistor in parallel that just trims some of the deep boom. More of a feel-at-gain mod than an actual revoicing.
In your situation I think a straight cap is more what you're looking for, but I felt obliged mention the de-mud as well.
