I don't know if anybody can tell you much about the converter. Almost all converter (performance)builders decal/paint some form of identification on their products. The company I worked for, stenciled the part number on it, put a decal on it, and most importantly, all performance converters had a serial number stamped into the body of the converter. With the serial number, we could tell what was done to the converter originally, who the original owner was, and what it was being used for, and if it had ever been sent back to us for work, what we did to it. All 360 converters have weights on them from the factory, but when weights are removed, then the B&M flexplates come into use.
Just a thought on my part, while the engine is out, maybe it's a good time to have the converter taken apart for a cleanout and inspection. There have performance converter builders mentioned by others on this board, so I'm sure one of them must be close to you. Not much help I know, but hopefully others can add to this. Good luck.
