Could anyone who has flown the YT (Modeltech) Magic Formula 3D give me some advice on engine choice?

I have a OS 91 surpass four stroke sitting idle awaiting a home. The specs for this model require a 70 four stroke. This would be my first 3d plane although I do have a fair amount of flying experience.

What is the performance like on a 70 size four stroke?

I know these have flown with a 90 size four stroke but am interested to know just how 'overpowered' this setup would be.

Thanks