Hmm.
First, I fly both of the p40s on occaasion, rarely though, for two main reasons. The ENY is WAY too low(40 for a plane that is only above the 234 and boston in the kill counts!, 35 for the one that just edges out the 202!) It doesn't help to have only the early war planes lack an "Attack" scoring option, which means those who care about thier score don't have much of an option to fly them.
The problem with the la7 isn't actually it's speed. The dora will dominate the la7 perked or not, because they're completly different planes. The dora is not an easy plane to fly, and because of that it mostly flown by better pilots. It may be fast, but it's level accelleration is marginal at best.
What makes the la7 weak is that it's usually fllown at low alts, making it fairly vulnerable to attacks from above.
What makes it strong is that, at those low alts, the la7 is able to engage in turn fights, roll out of it, and accellerate away from the fight, without trouble. The la7's speed, and turning ability is important, but it's the awesome accelleration next to it that makes it so lethal, and often so frustrating.
The dora may be fast, it may be excellent and uncatchable as a bnz plane, but it doesn't have the same abilities of the la7 in any way, shape, or form. The only way to justify perking the dora is to bring down the standard for perk planes, and perk all of the 1944 monsters.