Jive Turkey,
Dave will tell you, like you stated before, You will have to lean your motor out to get it to run right. It won't run right that rich at 2 1/2 turns out. it runs great at approx 1 1/2 turns out. YS 63 has some lifter noise. As long as your Gap is set right, go with it. don't forget you will need to check your Gap when the motor is cold.

Bottlerocket is right as well. If you have the smallest leak in your fuel system, it won't run right either. To test if you have any leaks in your fuel lines and system. Fill the tank about half full. Then with NO Glow starter, just turn the prop over about 20 times. Then let it set for a few minutes. then after a few minutes, take off a fuel line. If it makes a hissing sound. Your in good shape. Your fuel system is OK.

But you will need a tach to set this motor. You can't get it set right by tring to tune it by ear. Your low end will have to be set with a tach as well.

here is the link to how to set you low end.
www.ysperformance.com click on tech tips, then on YS doctors page. then it should tell you somewhere in there how to set your low end.