The JemVWH is fretted with 6105's. That's WARMOTH'S 6105 fretwire NOT DUNLOP'S 6105. There's a huge difference. I like them both, but lot's of people misunderstand, and reference the Dunlop size (which is very tall and skinny) The Warmoth 6105 isn't really a small fretwire, but it's not a mega jumbo like the RG's either. If you were "lucky" and there's a shim under your
lock nut, then Warmoth 6105's might only require removing the shim. But if there's no shim, or if you wen't smaller than 6105, the nut would have to be lowered. You can either grind a little off the nut, or route the channel deeper.
The trem should stay relatively in the same place. If it's almost touching the bottom of the cavity already, then I would route the front end of the cavity a little deeper. You can pull the anchors and re-drill them deeper, or sometimes if I just need a little more depth, I'll route around the anchors. It's like a "Tee" shape, because the underside of the saddles is deeper than the outer rims of the knife edges.
Another way to compensate for the trem issue is to route a slight
neck angle into the pocket. I do that a lot. Sometimes there are shims in there anyway, so I can pull them and re-route a clean, slightly angled pocket. That way the trem can come UP 1-2mm.