There are kits to make the lockup function correctly if your car didn't come setup with a lockup converter and ECU to control it. I'd gather that your car did not, so you need a kit or be crafty and build your own.
Next, someone has already asked how you have the TV cable (throttle valve) hooked to your carb. You need to confirm that this is hooked correctly with the correct bracket. Throttle lever geometry is absolutely critical to making this thing live. You can't just hook to any old post on the carb all nilly willy like and expect it to last long. If you, or your builder, did that, then it won't last long.
Lastly, the TV cable is the only input to this transmission for what the driver is doing. It is designed to let the transmission know when you're cruising, idling, and working it hard. It is properly set with a line pressure gauge. TV cable adjustments ARE NOT, REPEAT NOT, made to change how the car shifts. Any 200-R4 or 700-4R guy worth his salt knows this. The TV cable set incorrectly will burn up bands/clutches in less than 5K miles or couple of long burnouts.
Maybe get us some pictures of the carb and TV cable setup you have currently. If you need help with parts or tools needed, then let us know. FWIW, I'm not a trans rebuilder, but I know how to setup a 200 correctly. My son runs a pretty stout 200 in his car and works better than ok.
The biggest issue with setting the TV cable is that a fresh transmission and transmission pump will drive/operate properly with excessive or inadequate line pressure - it's kind of a real crapper because you'll think all is well.............until it isn't 🙁
