The Flickr account belongs to me. I am more than willing to share any information, but note that the sketches are just my own guesstimations. If you compare them to screen shots, the proportions (especially the wingspan) seem to vary considerably. I do not think the artists doing Nausicaa really sat down and figured out the exact size of the thing. I just took elements and proportions I liked and combined them.
That being said, one way to start estimating the size is comparing the Nausicaa Gunship when it is being loaded into the cargo hold. By using the Nitto/Bandai 1/72 Gunship, the minimum hold dimensions can be established (accounting for its width and height with folded wings). My sketches were ostensibly 1/200, but after doing this exercise, I figure they are closer to 1/250.