I don't know what all you have with your Tule, but from my experience, virtually every bike that came with a belt type torque converter can be substituted with a Comet system. They (44 series for example) come in the 1" bore.
The other option is to disassemble the engine, remove the crank and have it turned by a machinist. I'd only do that if I were madly in love with my vintage, or proprietary clutch.
Another option, and excuse my ignorance of the Tule, is to take your vintage clutch, for example a Deepco 3/4" (If that is what it is) and sell or swap it for another version of the same clutch with a larger bore, or sell it and make enough money to buy the Comet.
Shooting from the hip here, but you do have options that can end up with your bike looking original, but running and operating a bit better than original.