Well, there isn't a lot to this, so I guess I can chime in.
You can drop the bridge pickup down to take some of the shrillness out, or both down if the brightness is endemic.
Swapping caps is probably the quickest thing to try. Since you have one tone pot anything is going to be a compromise, but a trip to the local Radio Shack for a few cheap caps is your quickest fix.
Usually what's in stock will be the .047uf, .056uf, .068uf, .082uf and the .1uf caps.
I tend to want a darker tone out of my bridge pickups. I also use the Free Woman Tone mod from ChrisK so I can darken or brighten depending on the combination chosen and where I have the volume and tone pots set.
For a humbucker bridge specific tone mod I'll use the .1uf and the .068uf to get a .04uf in the middle position...and for single coils I'd use an .068uf and a .047uf to get .027 in the middle...but I'm not a fan of a bright bridge sound so your mileage may vary.
Playing around with a few alligator clips and different cap values will allow you to dial in what you like best.
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Turn down the Tone knob until it sounds right to you with volume ar 10. From there we can get an idea of what pot values might be best. If you cant get there this way then we might have to start talking about caps.
In general pot value has much more to do with "10 tone" then tone cap value does.
What can I do to tame this circuit and get a more dynamic tone with less biting highs?
You could change the wiring to series, but that will only affect the tone when both pickups are used together.
Working with the pickup height is an intelligent first step. If that solves or mostly solve the problem, we're either done or mostly done.
There a few different ways to "tame down" a peaky response from an individual pickup. You could load the pickup with a resistor. Experimenting with this is easy. Bypass the tone cap and your tone control now becomes a variable resistor. If you find a setting that sounds good, disconnect the tone control and measure the resistance at that setting. Install a fixed resistor of that value, in parallel with the pickup.
Or you could experiment with small capacitors directly in parallel with the pickup. This will move the resonant frequency downward. You'll still have a peak in the response, but it will be smaller and broader. This might be exactly right for you. Or it could make things even worse. Depends on the pickups and your personal tastes.
Finally, if you try different values of capacitors connected to your tone control, you might find one that does what you want it to at the low end, but the sound with tone on 10 is a bit bright. Perhaps it sounds just right for the brightest tone you want, when the knob is at 7 or 8 or 9. No problem. Just add a resistor in parallel with the tone pot to get the appropriate resistance value when the knob is at 10.
The added capacitance might be just what you need to tame those pups a bit. If your coils aren't already wrapped in electrical tape, I'd be sure to do that first. That way, if you don't like the shielding you can remove it with less risk of damaging the coils.
While I like TTH's answer (+1 worthy), I do have to ask, why not kill two birds with one stone, and install a set of Graphtech saddles? That'll get you what you want, tone-wise, and give you much better sustain, not to mention that the strings will tend to stay in tune a while longer.....
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