Be advised that the Topflite recommendation "40 to 70 cc" most likely refers to 2-stroke engines.
Your Saito is 53 cc, but it is a fourstroke, AND it is a radial. Meaning that for its cylinder displacement, it is not going to be as strong as a 2-stroke, by quite a large margin.

I have a similar (WRT dimensions, weight and engine outfit) plane, a Seagull FW190A powered by an ASP radial converted to gasoline, and that ASP is 65 cc but it still is no powerhouse,
Your plane is about the same wingspan, by its factory specs a bit lighter than mine, but by and large pretty comparable. The Saito is, for its size, a pretty strong engine, probably fairly comparable to my ASP despite the difference in displacement, but that still means you're looking at 3 hp tops and a 20 x 8 prop at best.

It WILL fly, don't worry about that. But it will not be a power monster.