flyer,
that engine will not work.
It does not produce enough power and is way to light. Your plane will be tail heavy; unless you mount the batteries behind the firewall or something.
The lower end engine required for this plane is a 91 4 stroke or a 61 2 stroke.

If you are on a budget a ST g90 for $119 with $33 slimline sport scale muffler will run you about 150 and give you more power than a saito 120.