Hi Tim,
The forest Cobra is a possibillity, nearly all cobra's have the ability to 'create' the 'hood' ...muscular movements extends the underlying long, movable ribs, and then is inflated with air from the lungs...the 'hood' is to give the impression that they are larger to potential agressors
http://zoltantakacs.com/zt/tv/04ng/s...bum.php?idx=17
"...The Forest Cobra is the second largest species of Cobra on earth. The RainForests of western Africa are home to this large predator, reaching lengths of over 7 feet this Cobra can deliver a very powerful bite to any would-be predator. Not afraid to stand their ground, the Forest Cobra is often regarded as an aggressive species in captivity...."
Other African species include the Red Spitting Cobra and one of Africa's largest Cobras, the African Black Spitting Cobra (can reach up to 7 feet in length) and are extremely aggressive in the wild. Both I believe are the 'hooded' variety.
Kind Regards David