Where is Widewing, when you need him? 
The Pony in the first picture, IIRC, is not a P-51 but an A-36 Apache/Invader, the first examples of which were fitted with 4 Hispanoes: not totally sure, but they should have seen combat.
EDIT: (oops Widewing beat me to it)
Not correct. Those are British Mustang 1a (P51 without any letter designation). I believe the British bought something like 160 of them which should be enough to allow perk versions in AHII if HT were so inclined. If he were I would most likely fly nothing else.
The A36 had two .30 caliber machine guns in the lower nose and four .50 caliber machine guns (two in each wing) and true dive brakes. If both were in the game I would have no need for any other airplane.