If You follow the Spitfire Logic and have a designer other than the original procede to undertake continued developement which included almost doubling the weight and tripling the HP then you could see the Gloster F5/34 and it's derrivetives go through a sequene something like this;-
MkI, Mercuary about 850/900 hp.
MkII, Taurus about 1200hp
Mk III, Herules about 1300/1700hp
Or Mercury, Twin Wasp, Merlin XX, Griffon III, Griffon 77, Hercules 100.
Or..