I believe VH-Rock has a proper P-40N in the works with the cut-out rear cockpit.
Well, technically using an M model would be a proper N with the N type FM... lol, since as said before the opened up rear canopy wasn't introduced until the N-5. It would need only 4 guns though...
From JBaugher's excellent website:
"The first production block was the P-40N-1-CU. It appeared in March of 1943, still powered by the Allison V-1710-81 engine, but with 122 gallons of internal fuel and a generally lighter structure than its predecessors. With weight reduced to 6000 pounds empty, 7400 pounds gross, and 8850 pounds maximum, the N-1 was the fastest P-40 service variant and was intended for high altitude combat. Maximum speed was 378 mph at 10,500 feet and service ceiling was 38,000 feet. An altitude of 15,000 feet could be attained in 6.7 minutes. Armament consisted of four 0.50-inch machine guns in the wings. Four hundred P-40N-1-CUs were built.
The P-40N-5-CU variant introduced a modified cockpit canopy with a frameless sliding hood and a deeper, squared-off rectangular aft transparent section to improve the rearward view. This cockpit canopy was retained for all the rest of the production blocks of the N version. The N-5 version restored the full six-gun wing armament, since pilots had complained that four guns were insufficient. Underwing racks were fitted for bombs or drop tanks, increasing external stores capacity to 1500 pounds. The new heavier gross weight of 8350 pounds limited top speed to 350 mph at 16,400 feet and service ceiling to 31,000 feet. An altitude of 14,000 feet could be attained in 7.3 minutes. Range was 340 miles with a 500-pound bomb underneath the fuselage. Three drop tanks promised a ferry range of up to 3100 miles at 198 mph. "