I found the information you were looking for.
http://www.autospeed.com/cms/article.html?&title=The-Nissan-VG30DETT&A=109870
710mm (27.95inches) Long
775mm (30.51inches) Wide
695mm (27.36inches) Tall
I wanted to know the size as well as I am planning on swapping it into my '93 Miata. Yeah I know, the miata swap is overdone, but the car was free to me so I'm going to make the most of it.