I counted on the spur 64t ,the bell is 22t ,but ,I noticed that my spur almost touches the a-arm mount ,so you may go with a smaller tooth on it an a matching bell!
However ,if someone else has a better idea of a base line ratio ,I would find a cheaper brand like Kimbrough to find a good economic ratio ,an then once satisfied with
that ratio ,then you can purchase a higher end brand like Robinson racing gears!