The Spitfire Mk Vb has the Hispano Mk I. Spitfire Mks VIII, IX, XIV, XVI, Seafire Mk II, Hurricane Mk IIc, Typhoon Mk Ib and Mosquito Mk VI all carry the Hispano Mk II. The US P-38s G, J, L and the F4U-1C carry the M2 20mm cannon which is the same as the Hispano Mk II for game purposes. Balisitically and for rate of fire the Hispano Mk I, Mk II and M2 20mm cannons are identical.
The Tempest Mk V carries the Hispano Mk V.
Hispano Mk I/Mk II/M2 20mm: 50kg gun, 20x110 ammo, 250cm long, 170cm barrel, 600rpm, 880m/sec muzzle velocity, 50,300 joules at the muzzle.
Hispano Mk V: 42kg gun, 20x110 ammo, 220cm long, 140cm barrel, 750rpm, 850m/sec muzzle velocity, 46,900 joules at the muzzle.
Data from Rapid Fire by Anthony Williams.