Q. I added about 2/3 quart of 10W-40, but I'm not sure if I see oil in the site or not.
A. Unless you know the level of the oil in a Virago, never add to it blindly. You can make a real mess by over filling the crankcase, and possibly cause serious damage to the engine by running it with too much oil.
If your Virago has been properly maintained and the oil isn't tar black and just sludge from not being changed at regular intervals, the oil will show in the sight glass with your bike on it's center stand. If there is no oil, you will see inside the engine through the glass and no oil. The oil in the engine should block your view of part of the inside, thus giving you the level. There are molded-in level indicators in the case cover (image below).