I once raced a BSA that had to be original. I adapted an old jap lever filing down the working end of the lever until it fit the BSA bar clamp. I just happen to have one of those levers on my work bench. I have no idea what it was originally on, but it has a true ball end, is made out of aluminum, and I would imagine that with some dremel and file work, you could make it fit the Triumph bar clamp.
If you haven't solved your problem by Sunday night, drop me an email with your address and I'll send the lever to you. When you get it, you can stick a $5 dollar bill in an envelope and send it to me.
Dick J
#729
"Worlds Fastest Bandit"