[Jonboy]

the raised flat area at the front is the actual lockup clutch. A normal 350 TC will be round at the front and rear.

I don't know a whole lot about the 350C. I do know that if the lockup is not working on a 700, it will overheat. Will disconnecting the lockup on a 350C do the same thing? I have had it happen when the speedo cable broke on my el Camino, and it got hot enough that the engine temp was raised. It also set a check engine light, with a TCC fault code. That is why I would be hesiant about just disconnecting it. If your trans is fine, it would get you by for a while. A regular 350 converter might be the way to go there. If you are putting in a converter, you almost have the trans out. If it is the original trans, then you have at least 17 years of use on it. That is why I would suggest a 350 swap, and it is (relatively) cheap, if you do the labor yourself.