PM me your e-mail address and I'll send you an Excel file that I use for an Arrow II where you just fill in the weight blanks and it plots your CofG on the envelope chart for you, if that's of any use.
It's also got a manual chart in it, in case you don't wish to trust the bone idle git's (i.e. ME) version.
Obviously you won't be using it though, as you only want to get an idea.