I would probebly go the other direction and error on the side of power! So let look at weigh vs HP of just the power system.
FA-40 is 300g
FA-56 is 410g
FA-62a is 420g <--- I like this one. It is closest to the HP of the electric motor.

fule - 100 - 200g
servo - 25 - 50g

So your total budget for wight with ht 62a is 670g

The E-Flight motor they recomend is:
Motor - 200g
ESC - 50g
battery - 300g

The CG will probably need to be modified by moving the engine back some. But I say go BIG! That plane seem to want a lot of static trust and you will want that bigger prop.