I have already figured out how to make the sounds that you had in AH2 appear in AH3. So, I could do it that way. Anyone could, I mean any one that knows how to edit sounds can make this work.
For me the most interesting part is making a Tiger sound like a Tiger, and an M4A3-75 sound like itself. When a P-51 passes by I want to hear a P-51, and I mean whistle and all.
As for cockpits, the first time through I paid a lot of money to take plane rides and record sounds. In some cases I was not able to get to a location, so I paid a recordist to do the same thing. I had just started out making sounds when someone (and I know who) gave my sounds to another sound pack maker. Professionals don't act that way, so I nearly quit making sounds for Aces High. When the tanks got updated and those battles started to heat up I got the bug again. So, about $50,000 later I have about 300TB of videos, and 35GB of audio to support making sounds. Most of the recordings that I got from inside of aircraft were really bad audio samples. Kermit Week's are no different, it's the nature of the GoPro system that just doesn't work well in a high SPL environment. The P-51 for instance is about 144db in the cockpit at takeoff, but the usual recording method is to hold the camera high so viewers can get a good view. Getting close to the canopy like that ruins the recording (my opinion). It's a mistake that I made recording a few airplanes before I figured it out.
What I did to correct the situation was to record samples from different points around the aircraft, and then mix them together until I got something closer to what your squaddies want to hear. As in my "Jugs" video from AH2, I used a mix like this:

I saved all of that work in my Sound Library. Anyone that actually makes sounds can take that work and modify it to fit FMOD and you will have the exact same audio in AH3, for internal sounds. That is
not what you want for external sounds. I think that's obvious, but there may still be a few people that haven't caught on. I'm sure someone will come along and do just that. I'm going to do what I think is right to begin with, and then
possibly come back and make things sound like AH2 somewhat. It all depends on a few things. Primarily, it depends on whether I can make the changes to my original sounds to correct for the rpm changes of AH3. I played with the P-47D25 last night and it seemed promising. RPMs are critical for AH3, so if you can't do that then you have to start over. So, when I started with engine changes I was on the right track to begin with.
And bustr, it won't be a situation where you have to wait for the whole thing to be completed. I believe I can do this as I move through the planes and vehicles. So, the first pack will be the M3, Fi156, Tiger1, and maybe P-51B & D. My own squaddies want the B-24 and B-17, so that may follow. I'm really wanting to concentrate on vehicles myself.