GoEDI said;
While you are correct, the amount of cargo carried would be nowhere near the 20+ tonnes that the Boeing figures take into account so I doubt runway length would be an issue to EWR.
That's true. Looking at the Boeing performance charts, it looks like a CO 764 could do EDI-EWR with a full load of 235 pax and maybe 12 to 18 tonnes of cargo depending on airfield met conditions, en-route headwinds, routings, cruise speed, cruise altitude etc provided that the EDI runway is dry. The Boeing charts I've seen don't state how a wet runway might affect these figures but I'd expect that they'd reduce the payload some more.