I will be interested to know what you find out, as I too have a set of TA Pro-5-Vis cranks that I am yet to mount on a bike. I thought that a Stronglight 118mm would have been long enough, but maybe not? I don't know what the standard spec. was for TA doubles, but surely it can't be any more than 118mm.
I was actually thinking of trying an old Sugino Mighty BB set with my crankset, as I believe they have an ISO taper, but maybe the spindle will be too short as well. We'll see...