Forgive me all for not reporting back sooner. Just now crawling out from under the bus.
I did get a chance to examine the Thunderbird lever up close (big shoutout to Triumph Detroit for allowing me to do so on their impressive showroom), and I'm afraid that the Thunderbird has an unique clutch lever that does not cross over to any of the know UJM models. And the difference is extremely small. No problem with the brake lever and as far as the clutch lever goes, the width of the pivot bolt boss is just a couple of millimeters different than say a Daytona or Speed Triple lever (I took several to test fit). I knew it would be close based on previous observations.
I'm not going to pursue this any further as my focus is on the smaller twins. Sorry to all who had their hopes up.
"With integrity, nothing else matters. Without integrity, nothing else matters."