It may help to mount all your heavy stuff as low in the fuse as possible. That fat fuselage hides the fact that the prop shaft is a long way above the ground.

I'm flying one of his R2's and it's a great flyer but a bear to land for just that reason.......you get it just about stopped and then it flips over and you go home and repair the fin and maybe the cowl.

As to power, I'm not sure what's 'enough' for the "Z". The R2 is designed for .60 2 stroke or .90 4 stroke and the YS 91 fz is embarrasingly too much!