Most bits I've seen you run the stock flat against the fence & the bit cuts the profile. Then you can cut your top & bottom bevels on the table saw. If I understand your question correctly & if you are planning to bevel the face & leave the back square I would advise against this. Most wall to ceiling joints are not perfectly flat or square. The solid square back of your crown will not be able to follow an out of square ceiling line without leaving some gaps. Using or making flat stock for this allows some give in your crown to follow the uneven surface that most ceiling/wall joints have.
There are 3 common angles for crown they are 38º/52º, 45º/45º, 52º/38º. The 38º/52º is used for the shorter ceilings such as 8' high. As the ceiling heights gets taller the angles should change to view the crown from below.
Have a nice & safe day!