Totally agree with 350 on front wheel, especially with those tapered forks even though they're steel. Too much power and weight up front; those 1000w direct drive motors are very reliable, but also very heavy (as much as 20 pounds). If you want to try a front hub conversion, my recommendation is a 350w,
geared hub (less than half the weight of the DD motor). Even then, use at least one torque arm. As he said, the ramifications of a front failure aren't pretty.