If you have a lot of building experience and "SWAG" experience, it should not be a problem. Like you say, it's a matter of sizing the wood so it does not get "overbuilt". Thats where a lot of kit experience will help. I believe cowls can purchased from most glass companys as standard round cowls. The rest will need to plugged and molded, or carved from block. At 80" should be a nice size plane.
You might look at American Eagle Aircrft, they have a glass & foam kit for the D-18 at 82"
http://www.flyrcmodels.com/