"The p40e does not perform that much better than the b, but the guns would help. "
P-40B
2300 FPM maximum climrate
276 MPH at sea level
342 MPH top speed
P-40E
3100 FPM maximum climrate
297 MPH at sea level
352 MPH top speed
A6M2
2800 FPM max clirate
270 MPH @ sea level
328 top speed
Ki-61
2900 FPM max climbrate
313 MPH @ sea level
368 MPH top speed
The most signifigant difference is of course the vastly improved performance under 10K; P-40E can outclimb the A6M2 by a signifigant margin up to about 11,000 feet and is almost 30 MPH faster. The A6M2 does not enjoy an advantage until above 15k, and how much fighting is done at 15K (where it still has the Wildcat to deal with)?
The P-40E may be historical in this setup, but I wouldn't necessarily call it balanced for gameplay. The Ki-61 is the most balanced match against the P-40E
J_A_B