Pete, you don't have any units in here that will directly link together. Depending on what you're trying to accomplish, possibly the best (easiest) way to go is to use a relative log exposure scale. That is, just make up a value for a certain exposure. For example, say the log exposure scale is in "Pete Caluori units", where you define how many units at a certain exposure. From there, each doubling of exposure increases the log exposure Pete units by 0.301.(posted 8731 days ago)For example, maybe you would call that 1/60 at f/11 exposure 0 log E Pete units. In that case, 1/30 at f/11 gives 0.30 log E Pete units, 1/15 at f/11 gives 0.60 log E, etc. Decreasing exposure goes the other way to -0.30, -0.60, etc.
I can't think of any reason why you need absolute units for this except to actually measure an ISO film speed. In that case, you'd pretty well need a sensitometer with known power output. If you just wanted to compare speeds of different films, the relative method (using log E "Pete units") would work just fine. You can also plot sensitometric curves, etc
Will this scheme get you where you want to go?