instead of worrying about your final drive so much try and use roll out instead here is the formula for it
pinion/spur *internal drive ratio /tire diameter
i run a 10.5 turn brushless at 33 mm roll out and have power when i need it
my gearing is 48pt
pinion 27t
spur 72t
internal drive is2.25 up front and 2.18 down back(used a pulley from tao4 35 tooth not 36
72/27=2.66*2.25=6.0
tire diameter is 64mm*3.14=200.96
200.96/6=33.49 mm roll out
if you need to add weight place it in the centre line under the belts ,