A dumeril's boa might be something for you to consider in that case, (I don't have one but have lately been checking boa's out myself), they "can" grow to about 8.5 feet but as far as I know that's not common I've heard that they usually grow to around/near to 6 feet, http://en.wikipedia.org/wiki/Boa_dumerili (there's a page on them for you).