A friend here has said to me that FL hr alto ligature is the same size as a tenor L. I have one and i would try it when the piece arrives.
Different taper, differente pressure plate and different "smart cap".
The other is the same, but these three details are not.
I got an OctaSupreme... it worked with standard tenor ligatures.
A "L TEN" François Louis will ruin the body... and the lig itself.
Table and facing are beautifully finished so you'll not get any advantage from a FL lig (as long as your reeds have a flat table, not convex).