767-4 great for punters just a nightmare to balance. It needs decent engines and a larger fuel tank. All boeing did was use the same tank as 7672. Engines only slightly better.
Now for an aircraft that is 50ft longer and a MTOW of some 55,000lbs more you dont need to be a maths genius to work out that this a/c not all it is cracked up to be. Would be great for charter runs through the med but anything over 9 hrs and it struggles.