No, it's pin 6, as is 'clearly' shown on the PCB layout.
I've just tried to find the original article, and I'd have posted a better scan - but I can't find that issue.
It's from 1981, so 30 years old - there were a number of Syn???? projects that year, and the magazine ended at the end of the year, and became 'Electronics - The Maplin Magazine'.