You mention a "internal fuel leak"...is it like a welch plug is missing somewhere in there? The "runs at idle but stalls with throttle applied" thing can be a variety of problems; from an air leak between the carb and the motor, to the float having a microscopic hole in it which is allowing it to fill up with gas and sink, or even as simple as an adjustment or a hidden dirty carb or passage that may have been missed during the 2 rebuilds you mention. Typically on a small engine, the float needs to sit level with the body of the carb while lying upside down on a level surface, sometimes it is a little over or under level which is determined by a float level gauge. The float level would be specified in the specification/shop manual for your engine. Your float could be off as someone who wasn't familiar with this engine could have been forking with it when they rebuilt it. sometimes you put a new needle seat in, and it changes the adjustment of the float. Try to find a diagram of your carb online by using the engine model numbers or the numbers stamped on the carb and then compare it to what components you have with your actual carb. This way you can tell if something is missing and you aren't just guessing and trying to describe the problem to someone else.
I should mention that these Chrysler engines are very cool as are Rokons, they are an excellent piece of robust American and Detroit history. We need to preserve as many of these Chrysler engines as possible.