db, I'm really interested in hearing how the sonicaps work out for you!
If I was doing it, I would replace the big 2.2 caps with your new sonicaps.
That way I could use the jumpers to switch back and forth between the
original cap and your new sonicap. By moving the jumpers, you could
quickly switch back and forth, to facilitate a comparison test for sonic differences.
As far as voltage breakdown, the 200 volt rating should be fine.
But, a question arises as to the possible sonic differences
in a 200 volter vs a 600 volter... aren't the 600's larger in size?
Good luck! Sounds like fun.