Quick back of the envelope/piece of string calculation makes me think a 777-300 could probably manage LHR-HKG routing via Iran but no promises - it's tight if you want to maintain legal reserves and I suspect you'd be losing payload...
Basil
Looking at the logbook I did the LHR-BOM-HKG trip a couple of times in the summer of '90 on the 747-200 ( on one trip I had the added delight of a BOM-DAC shuttle). On the second one I remember running into you senior chaps on the 744 in the pub in HKG since as you say you were doing the non-stop - that cheered up my captain (the brother of a well known footballer
) no end and put him in a fine mood for the slog back home via BOM........oh how we laughed........
(FWIW I escaped to the 744 about a year later...
)