Hi I had similar problems. Mine squawked and squealed, kept pulling fan into alternator housing and grinding it, etc. And all kinds of problems with pulley mount shearing, slipping bending.
I tried to reinforce mounts, neplaced alternator, fan, all sorts of things, to no avail.
Finally i just went to a GM/Delco alternator conversion. About $50 rebuilt from local auto parts place. Had to also find a pulley with the same belt grooves as the supercharger belt, but with careful location of the alternator and bracket was able to make the conversion using the original Moss serpentine belt length. So far been on over a year working great. Once i puzzled out the conversion layout it was actually very simple and looks really sweet. Not stock but if you're s/charged thats no longer an issue!
Basic info on the conversion itself on TR website and also Bill Masters electrical book.
I can send pics if you want. Also can dig up info on where i got the pulley etc.
Just let me know.