Let's end this one then once and for all!
FCO opened in October 1993 and closed earlier this year.
During that time GF operated B767, A330 and A320 on that route's scheduled services ex the Gulf.
It is also possible that an A340 has dropped in as well ex LHR during times of disruption.
So in fact FCO had seen all aircraft types that GF has in its fleet over the last several years.
PS: heard a rumour today that Oman are now prepared to front up. They need the GF business at MCT otherwise the BAA (who recently acquired (wheres my dictionary!) the airport in partnership for development) may pull out!