I built that kit when it was released back in the late seventies.I do remember a fit issue between the upper body work and the monocoque at final assembly.The body work seemed to fit fine prior to that,but when it came time to drop the upper body on for the final time it didn't want to snuggle down all the way to meet the side pods.Be sure that all the piping and hoses are tucked out of the way before you drop the upper body down and be sure the side pods are fit properly.Good luck!
P.S.-I still have the model but it now sits in my basement slowly dis assembling itself