Ditto, I hear ya.

Usually, the smallest engine recommended WILL fly the plane, but often just barely. Whenever I build a kit, I install the largest engine recommended. If I have too much power, I can either throttle back or use a larger prop to absorb the H.P. As you know by now, you should have installed, at least, the .90. If the engine you purchased is still unused, you may be able to return it. If not, keep it for a future project or sell it at your local club or on eBay. Personally, I would NOT attempt to fly that plane with that engine.

You state that you're still new to R/C power. Are your capabilities up to an Ultimate?

Dr.1

PS Next time, you might want to ask more experienced R/Cers first.