Bwog... make sure the map merits that number of territories. This is by no means intended to offend but many before have claimed their intentions to make such a massive map only to have a miserable design or simply get overwhelmed by the level of effort involved.
I'd recommend discussing your idea for such a large map with one of the experienced mapmakers (not me) to get their opinion on its value. If it's like [this debacle](
http://warlight.net/SinglePlayer.aspx?PreviewMap=9665) then I wouldn't recommend proceeding since it simply won't be worthwhile.
Again, I don't mean to offend... I just recommend vetting the idea out before spending the necessary effort.