That plane would fly on that size Saito but it would be very borderline for power. If you make a mistake then you will have no reserve power at all to get out of it, but I do not seem to remember Saito making a 45 size engine, I know they make a 40 and it definitely would not be enough. I used to have that plane and on a 46AX by OS it was a perfect match, then I went to the Saito 56 and again a perfect match, just used less fuel

The Fourstar series planes are very forgiving but need some power to really fly well, read that as do what they really can do