JCA22H Depth Mod

Bod

I'm interested in having a go at this, but I want to make sure I get everything straight before I start placing orders.

Now, on my JCA22 there's a point on the main PCB labelled NFB and a corresponding point on the rear jack PCB labelled the same.  Am I correct in thinking that I'd simply unsolder the wire between the two and insert the pot and series cap in it's place?

Also, what sort of voltage ratings should the components have?