It's something like an average power of 170kW to get to 60mph in 4.0s vs. an average power of 220kW to get there in 3.1s. So that is 77% of the average power required in the P3D. After accounting for whatever contribution the front motor makes, it's very likely that the requirement to maintain that 4 second time is less than the ratio 630A/840A (75%). (The amps determine the torque, not the power directly, obviously, but you can still use this as a proxy without the exact numbers - would be better to compare the acceleration (which is constant) from 5-45mph to get an idea of the requirements...but I don't want dig through posts here to look it up.)
Anyway, so it seems very likely that with the (speculative) 630A peak current "LC" motor, it would still be plenty to maintain the 4 second time. If the 990 motor has the 630A inverter, it should be enough for the AWD to meet the published performance numbers. Data would be good of course.