the spit V did come clipped as the (gets my spit book ) LF VC and LF VB . most of the med and NA spit V's were clipped as high aly work was done by spit IX by that time of the war (in Italy). i have operational photos to prove. On the 4 20mm note . Spit VIII in the far east would fit the 4 20mm when they were given ground pounding rolls (quite common by the end of the Burma campaign)
the seafire Mk XV saw service in 1944 and was griffon engined climb rate of 4000 Ft per min and top speed of 390 Mph . It also had the Mk V 20mm cannon wich had a higher rate of fire and shorter barrel.