I feel that the alternator pulley may be the suspect. My reasoning is that the alt. pulley is a clutch type and designed to operate in one direction only. I speculate that due to the additional drag imposed by the KB and any slip realted to this, particularely during high RPM and shifting, it jerks the belt and causes it to slip off or even break.
Hmmmmm, now that is good thinking.
I have the ability to machine just about anything. What do you think about me making a alternator pulley with a big "shoulder" on the ouside edge to in effect keep the belt on the car?