Boeing Vertol studied several GETOL configurations and finally settled on the Boeing-Vertol Model 129 (i.e. BV-129), "a twin fan hollow wing Ground Effect Take-Off and Landing (GETOL) Flight Research Vehicle powered by one Lycoming YT55-L-5 engine."
Below is a composite plan I recreated using the poorly scanned documents in the report as a basis.
Source: TRECOM Technical Report 62-63, AD 401149 (U.S. Army)