The over the nose is the same as the spit IX and VIII  but it is poor when you compare it to the P38 , hurricane,  P40 , La family  , brewster , 205 , AM6 , niki , so on and so forth . Again small fuel load compared to other fighters .  Any way all those add up to non perkieness , after all some asked for bad points about the spit IXLFe . The gun package is small compared to the P47  or some of the FW190's  and Bf 109's . it wasn't meant as a comparison just to other spitfires , but I did point out where it wasn't as good as other spits  where it did perform better than most aircraft  but fell below other models . 
I wanted to show that there were quite a  short falls to it  that means it's not perk worthy . 
 Personally i prefer the 4 .303 but then i tend to fire when I'm at 200 yards or less . 
*psst guppy perking the XII for every one bar yourself  you don't want anyone else flying it surely?*