Design work for a probe on aircraft with an underslung canoe is totally different to one for an airframe with a very large radar array on top of the fuselage....
Reading reports the original Saab radar had a maximum range of about 180nm. The new ER version supposedly has a range 70%, but it only flew for the first time this year, so not trusted in service. It apparently has 5 operator positions, but size wise the Shackleton would have been commodious. If I wanted 12+ endurance I’d want a rest area and room for expansion.