Any time you change parts that could change the cam timing its not a bad idea to degree things but its only accurate if you have the 'cam card', that is the specs of the cam that is in the engine. With the smaller companies this is often a hand written and measured on an actual card. If you have the card its worth doing just to be sure its right, it could save you some head scratching later. Since you have the crank key, both sprockets and the cam key or pin it does not take much (even normal tolerances ) to get off enough to make a difference for some applications.