John, there is an RCM&E version of this plan, identical except for the built up wing and tailplane, and showing either removable tailplane halves or fixed. The belly pan on this version is built up balsa, so maybe you have one of the foam/glass kits that proliferated after the plans were published. I don't think the construction article in either magazine was what could be called 'comprehensive', you were expected to know what to do if you were considering building one of these things. If it flys anything like my Atlas you will be a happy man...
Evan, WB #12.