I money were no object, a military A340.
It would have the fuselage of an A345, but stronger floors for cargo, plus a side freight door.
But the wings/engines of an A346.
Also, one hose for refuelling large aircraft under the rear fuselage, and two hoses for fighters, one under each wing. In other words, the standard RAF tanker layout.
Above the cockpit, a probe for taking on fuel in-flight.
Then the usual military equipment like secure radios, additional nav. gear, ability to be flown while crew are wearing chemical/biological protection gear, missile warning/jamming equipment.
22 of these would be built, plus 2 without the refuelling gear for crew training/pure transport and squadron support plus of course VIP when required.
Sounds outlandish? In the mid 60's the RAF got new VC-10's with the standard fuselage, plus the wing and engines of the super variant.
They also, unlike the civil VC-10s, had an APU.
Also this would be by far the best solution for UK industry, and would give the RAF, (who remember are deployed all over the place, often in action), a highly capable tanker/transport with impressive range and lift, plus not too bad a runway requirement for a civil jet, though not a real short-field jet like the VC-10.
But money is an object, and it aint a perfect world.