Early wooden delay line cap voltage rating - wasn't there a thread on this?

[enor]

Was just about to start recapping the delay line of my AV, when I look and see that the caps are rated 600V, rather than the 200V that are otherwise common on generator etc.

Then I sort of remembered that there was a thread about this here, but I can't find it. Someone had done the math and found that there is actually cause for a higher rating on these caps in the old "CV" type circuit...

But again. I can't find the thread. Help!