I think Sandy King has done some comparisons of different light sources that might help up get in the ballpark.
But one even has to take into consideration the heat generated by the bulbs and the resulting temperature of the pigmented gelatin during the exposure as well as all the other factors I gave earlier. I just have a feeling that all these variables would make knowing the exact UV output of the light source to be of little practical use. Sort of like wanting to know one's air speed after a wing has fallen off.
But it would be a nice thing to know why my tissue seems to take one to two stops more exposure than just about everyone else's (probably my low pigment concentration, though). But my exposure under a 750W Merc Vapor bulb is about 90 minutes (about 12" from the neg), while Howard's is 6 minutes under a 1000W "multi spectrum" lamp at 21" from the neg! That is some difference!