George Lucas = CGI
1) There are 4 P-51B/C aircraft still flying. 2 of them are painted as Red Tails aircraft, "Ina the Macon Belle" of the Collings Foundation, and "Red Tail" of the Commemorative Air Force. For insurance purposes, these aircraft are valued at somewhere around $5 million apiece, however if one was lost, there are no replacements. Red Tail just got restored after being belly landed back almost a decade ago, killing the pilot. I doubt they'd be able to do it again. Additionally, the aircraft cost upwards of $2000/hr to operate. Flying the kind of scenes required also risks blowing an engine, which costs well over $100,000 to replace/overhaul.
2) There are *NO*
airworthy early model P-40s flying.
3) There are a few early T-6's flying, but very few and again, because they're rare, they're very valuable.
4) The FW-190 and Bf-109 are even more rare aircraft.
4) The insurance coverage required for live air-to-air filming is exorbitant and that's *IF
the operators are willing to even risk their airplanes in such operations, especially air-to-air that requires air combat maneuvering, something very few operators will risk.
In the end, CGI is the only way to go if you want to make a film like this. It's just not financially feasible to do it with the real airplanes if you could actually get them. Tora! Tora! Tora! will go down in history as the last time Hollywood could afford to make a mass of replica aircraft for a movie because at the time, there was a glut of aircraft to do it with. Since then, even most of the Tora aircraft have been scrapped or crashed.