Right now my rank is in the 130 range (started late in this game).

Thinking about hitting a top ten country (they double hit me a few times) but can't since the other country is too large.

If I declare war, does the "Other country is too large" block go away?

Nope. On primary the max NW you can hit is 4x your NW regardless of war or GDI.

Likewise the smallest guy you can hit is 1/4 your NW regardless of war or GDI.

Declare war doesn't actually exist on this server. I think some messages might refer to needing to declare war but if so that's misleading. Simply can't do it if they're out of range. You can always try to get back into range. They have to grow 4x as fast as you to keep you from coming into range.

The higher ranked countries will start to stockpile soon enough. Their networth will stop rising while yours will continue. Soon enough your target will come into range.

And hits suffered while stocking are particularly painful. :)

Good luck.