When trying to refit the body to the chassis after some work it is very likely that it will seem to be a difference shape. The number of packaging pieces between the body and chassis may not be the same as when the body was taken off. If any parts of the chassis have been replaced or repaired the shape of the chassis may have changed.
You can get a copy from my website at http://vitessesteve.co.uk/ServiceTrainingNotes
The workshop manual has details of what shape the chassis should be again copy available from my website..