I used to think about building an AWD F2T but quickly came to my senses after smoking every AWD I ever raced on a roll. (or Smoking everything I rolled).
The F2T's strength is upper gear acceleration and if any of that gets sacrificed for launch then the best part of driving an F2T gets ruined. Remember power gets cut down to the highest number of the front/rear split so a 40%front/60%rear AWD would put down 60% of the power the same car as a RWD would (FWD has the least loss to the wheels so it would be less that 60% of a FWD), on average AWD cars are 800 to 1000 lbs heavier than a FWD or RWD car which represents another large loss in power.
The 323 GTX drivetrain would get shredded by the F2T's torque curve, The 3rd gen 1990 and 1991 626 4WD came with the F2 2.2L 113hp 131lb-ft as the largest engine option, if I recall is wasn't as strong as a standard H5M-R (F2 N/A FWD 5speed) the only good thing about the 626 4wd was it was still a light car despite the 4wd system.
JFSmith you need more than the rear struts and brakes... Look up converting a FWD to RWD, you need the rear strut towers and floor between them the rear diff assembly and carrier, to raise the tunnel to accommodate the drive shaft and probably need frame rail work to handle power coming from the rear.
The Mazdaspeed6 drivetrain was a good idea and a better way to put power to the ground than Subaru's and Evo's, it was the reverse of the nissan R32 GTR that launched AWD and went RWD under traction which made it faster than the AWD competition with the same HPR. How does the Mazdaspeed6 computer controller drivetrain work? Can you send a piggyback signal to the rear diff to shut it down- Yes, how easy would it be?.
But the Speed6 FWD under traction unfortunately didn't help it because the car weighed so much because of the AWD system -immovable object meet the unstoppable force- Perhaps if they put a real engine in the car instead of the 2.3L aluminum paperweight.
The best solution to launching an F2T would be to custom build a rear end to accommodate two electric motors and small generators, toss some lithium batteries in the trunk and use an UNO3 controller (22$) to operate the electric motors.
You would need to add a speed sensor to the car and measure the output signal at what speed you no longer need the electric motors (when you stop spinning as a FWD), program the UNO3 so at that imput voltage the output signal to electric motors is cut (through a relay), you can add a 12V toggle to signal the UNO3 in and out of launch mode.
Then you just measure the TPS output (it's a potensiometer) at wide open throttle and piggyback the TPS output to the UNO imput and program the UNO so if it doesn't see wide open throttle for 2 minutes than it turns on the 2 generators at the rear wheels, monitor the batteries charge status send the signal to the uno and have it turn off the generator relay when they are charged.
The only thing that might need working out is throttle to the electric motors of course it can easily be done with the gas pedal but people usually launch full throttle so The UNO3 and Speed sensor could be used to put out a power map to the electric motors something like 5mph-56% power, 10mph-69% power, 15mph-88% power, 20mph-100% power. But my guess is a speed sensor would put out 0-5V in 0.01 volt increments so 500 points of measure so the map could be far more accurate.
And yes the UNO3 can be used to control electric throttle flap position on a gas engine with the gas pedal to the floor as a form of launch control.
Don't want batteries, run a gas generator and two car batteries in the trunk to run the electric motors.
But if your hell bent on an AWD F2T, you will invest time and money, you don't want to build it around a drive train that can't handle the sudden torque of the F2T, You don't want something rare or hard to find either, less than 1300 GTX's were imported to north America (If that's where you are), the Mazda 323 GTR transmission should take the F2T power but after importing one if it ever breaks would you import another?
I would look at different gen Lancer EVO's the early ones have the transmission on the passenger side (5 reverse speeds) the later ones have the transmissions on the drivers side, You would need the transmission, front CV joints and drive axle and shifter assembly, look up the rear end gear ratio and get a mustang (or any rwd cars) rear end (+ all you need) and rear diff with that ratio, aftermarket mustang parts are cheap and easy to find. Or find an evo with blown or no engine that was hit in the front and buy it at a low price.