What is the relationship between rod action (fast, moderately fast, slow) and Modulus?

In attempting to buy a fast action blank of 57,000,000 modulus to build a new rod, I called a supplier and was advised they could not get the blank I wanted -- it was back ordered and delivery date was unknown. The company then I called suggested that I buy a 37,000,000 modulus blank instead and that it would be as fast or faster than the 57,000,000 blank. This doesn't make sense to me as I have typically used a relatively fast action Sage XP that I believe also has a relatively high modulus.

Althought fast, moderate, and slow action may be somewhat subjective,it would seem to me the faster action rods will also be of a higher modulus.

Can anyone out help me out on this issue?