Well Juzz, the -3 engine, while not uncommon among early B models was replaced by the -7 well before the end of the B's production run. Further, the -7 was in all C models.
Now while the -3 was arguably a better engine at high alt than the -7, it should be noted the B/C was a better PLANE in most respects than the D model by all accounts.
After the Mustang III aircraft had been delivered to England, the RAF decided that the hinged cockpit canopy offered too poor a view for European operations. A fairly major modification was made in which the original framed hinged hood was replaced by a bulged Perspex frameless canopy that slid to the rear on rails. This canopy gave the pilot much more room and the huge goldfish bowl afforded a good view almost straight down or directly to the rear. This hood was manufactured and fitted by the British corporation R. Malcolm & Co., and came to be known as the "Malcolm Hood". This hood was fitted to most RAF Mustang IIIs, and many USAAF Eighth and Ninth Air Force P-51B/C fighters received this modification as well...[/b]
...However, many pilots regarded the Malcolm-hooded P-51B/C as the best Mustang of the entire series. It was lighter, faster, and had crisper handling than the later bubble-hooded P-51D and actually had a better all-round view. Its primary weakness, however, was in its armament--only four rather than six guns, which often proved prone to jamming. Some of the modifications applied to the P-51D to improve the ammunition feed were later retrofitted into P-51B/Cs, which made their guns less prone to jamming. With modified guns and a Malcolm hood, the P-51B/C was arguably a better fighter than the P-51D, with better visibility, lower weight, and without the structural problems which afflicted the D. Its departure characteristics were also more benign. (j bauger)
This is the plane I expected. It's unfortunately not what we got.

The one we got has no discernable advantage in handling, has no noticeable edge in accel, seems to miss the numbers on climb and speed, has no hood and falls apart just like the D does when hit.
Now, in HTC's defense, the IS a pretty good early model B... (except for the benign handling and durability) but it ain't the plane of legend. Maybe next time out we'll get a P51C or Mustang III.
Specification of P-51C-10-NT:
One 1695 hp Packard Merlin V-1650-7 twelve cylinder Vee liquid-cooled engine. Maximum speed was 395 mph at 5000 feet, 417 mph at 10,000 feet, 426 mph at 20,000 feet, 439 mph at 25,000 feet, 435 mph at 30,000 feet.
... but thanks for asking Juzz.

Hang