Yes, 2ft above the chain stack would be good. You could live with less but chain has a wierd habit of stacking up vertically really well instead of falling over!
You need to decide if you want Horizontal or Vertical windlass. Surprisingly, the Verticals (Maxwell and one other) I've had have worked super well for all chain rode
. The horizontals are trickier to get enough chain to wrap around the wildcat well. The horizontal with the drum and wild cat are easier to use for 2 rodes, or other non anchoring
taskes though. I'm pretty sold on the Vertical Maxwell
chrome/bronze ones. They catch sheets
etc less than the horizontal also and dont take as much above deck
space. Plan easy quick access to the anchor rode storage