Hi Waldo,
It appears (from your example) that you wish to determine first, the appropriate Dunning Level before choosing the suitable Dunning Activity. If you wish to derive an appropriate Dunning Level via custom logic, then you can enhance Event 304.
Consequently, if required, to determine a suitable Dunning Activity for that Dunning Level - if your logic requires parameters other than Creditworthiness Score and $Amount, then you can utilize the Event highlighted by Amlan, above - otherwise, you can achieve the same via standard configuration.