I don't know a whole lot about them, but what about a white lipped python? From what I understand Northerns top out around 7-8 feet and Southerns get closer to 10 feet. The Northerns appear to be at the top of your size preference, but after a very quick glance around the web they might be something you'd be interested in. Maybe check them out and do some homework?
this is a really poor recommendation. If you are unfamiliar with the species, probably it would be best not to recommend it to others.