That makes almost no sense. a C550 sized AEWC will be too small for the PLAAF, considering the size of the country and the long endurance required.
I expect a future AEWC based on the Y-20 but that's years away and the PLAAF seem unwilling to modfy more Il-76s to KJ-2000. KJ-200's may make up the gap well but the lack of full 360 degree coverage may be an annoyance -- there's the ZDK-03 with its mechanically scanned AESA on the same Y-8CatIII platform if they want it. But any smaller than the Y-8/9 sized platform for PLAAF and you're going into a grey area between PLAAF's AEWC and PLANAF's carrier AEW.
A G550 based solution would theortically be cruise about 10000 ft higher than a IL-76/ E-3 sentry ... and have about the same endurance. the only limitation is power supply and interior volume / crew fatique.
notice how both ASTOR and Israeli Phalcon solutions settle on a biz jet platform.
bigger wing, bigger tankerage, bigger engine = long endurance, better climb performance, higher cruise ceiling.
what one really need is a bigger winged, inefficient airliner.
current batch of airliner's engine and wings are sized for climb cruise starting at 20some thousand feet and may be reach 40000. as a
they demand higher wingloading to save fuel. relying on complex flaps to extract max lift for low speeds.
contrast some of the fullsize biz jet initial cruise starts at 30000 ft.-ish. and they usually dispense with complex flap systems.
turns out bigger wings also does lower your stall speeds at higher mach numbers... you say what? yes, where stall speed meets the buffet boundaries. turns out awacs, because of their loitering time (not range) requirements, flys at a speed closer to their stall speed than the speed a airliner flys for range. also big wings always carries more fuel.
so where is climb performance comes in? that determines how fast one can be on station. important.
actually 787 is a good airplane in this regard. its engines are oversized so is its wings.
climb performance in airliner is also important. help avoid time-delay and fuel costing route changing issues in bad weather conditions.
that's also the reason why 777 beats a340 hands down. turns out two big engines designed for single engine out climb, does wonders for all engine climb performance
oversizing paid off unexpectedly.
Oh lets' say 777 vs A340 service in singapore airlines service during pesky monsoon season should amplily demonstrate that.
anyways, rambled way off topic.
my point is one is wise to choose a platform for these surveillance platform with 1) big wings, 2) big wings 3) big engines. so one can get maximum 1) altitude, 2) loiter time, 3) climb performance.