First off, welcome aboard here.
This problem of your's sounds strange. I have never heard of a torque converter acting this way. A 3000 RPM torque converter is pretty serious, so I assume there must be tall gears involved in the rear end?
Just off the top of my head, make sure the throttle return spring on the carb is doing it's job. If it's weak, that can cause a higher RPM. Other than that, this does sound like a tranny problem, and that is not my strong point in knowledge.