From searching the net you come across so many errors.
Here is one related to this topic. It appears to be "official" Donington Grand Prix Museum site
http://flickeflu.com/set/72157616386876693
Go down to photo # 15. It is described as Chris Amon's Ferrari 312.
In fact it is a 246. Subtle difference is 312 had 12 cylinders, whilst the 246 had only 6.
Unfortunately one just has to be so cautious not to be "thrown out" by what one reads.