Have you considered the 'E' word (electric)? I've built a few multi engined models using glow power but never again. Even using basic & proven low tech electric power this type of model is not just possible but a practical, fly it every weekend proposition. Check out this site
http://www.geocities.com/ivansplans/ and this one
http://users.bigpond.net.au/BAC/B-36_video_page_.html
The B-36 is a little bigger in span than what you are planning but only 10 1/2 pounds - lightness is the secret. A Super Connie is on my 'to do' list but it just has to be electric, any other way is the hard way. - John.