On the Bentley web site - they have a few corrections which should be printed and/or manually edited in your hard copy for the SC manual:
Cylinder Heads, Installing
Distributor rotation - page 280-2 (P983)
Wheel brearing cover plate tightening torque correction - page 420-20 (P983)
https://wiki.bentleypublishers.com/display/tech/Porsche+911+SC+Service+Manual+-+1978-1983+%28P983%29+-+Updates