Many early MkV had MkI wings (and fuselages
)
Neg G is not near zero G. From the excellent source posted by IvanK (AAAH if all the doc posted on internet had the same trusty quality) , we can see that 0.2G was the design limit.
Neg G IMOHO would hve needed a MAJOR redesign of both the carburetor and the fuel supply line. The pumps are far from delivering a sufficient pressure differential). This would be interesting to investigate (both on historic doc and on Warbirds flying nowadays - ie are the Spitfire flying today fitted with US-made pumps ?)