According to Honda's GX200 web page it takes 20 ounces (0.63 US quarts) to fill the engine.
According to the Owner's Manual, SAE 10W-30 is recommended for general use. There is a chart in the manual with a temperature range for other viscosities.
There may be some residual oil in the engine from Honda's testing, so go easy as you fill it so it doesn't overflow.