The engine was designed to be a kart class engine that is out of the box like some others. If you want to build a engine, this is not a cost effective piece to start with. There are others as mentioned that are better suited for a build.
Ive used those flywheels for years in riders and racers. I have had the fins cut down some as well for race bikes. The timing is 22 BTDC as SAS289 has already mentioned. I use 10* or 12* keys with them. Check with timing light to confirm what your target is.