The gravity fed hvlp guns (with the cup on top, as seen in car body shops)
require much less air and probably can run on your compressor.

Actually, HVLP guns consume a lot of air (High Volume Low Velocity) and the
type of guns used in body shops typically require an industrial-sized
compressor. Also, the type of feed doesn't affect the air volume needed to
atomize the finish. Many manufacturers offer the same model in gravity feed,
siphon feed, and pressure feed, and the air consumption is the same for all
configurations.