I am trying to get my head around using a flash head for still life.

The head I have is a 200w/second with variable output.

Scenario:
I have set up a still life and using just the modelling lamp in the flash head and some small bounce cards, I have found the lighting which I like, quite moody and lowkey.

The part I am struggling with is knowing what power setting to use to reproduce what I am seeing with the modelling lamp.

Am I on the wrong track here, should I be just using the modelling lamp as the light source and forget about the flash ?

The reason wanting to use the flash was to stop me wandering into reciprocity and also prevent image movement through a long exposure.