If the pump goes out on a freshly rebuilt trans because of convertor installed wrong will whole trans need rebuilding or just pump replacement??

 

I don't have personal experience with this, so let a pro confirm or correct me ...
If the engine was not started, then you might only need a new rotor or at most a new pump.
However if the engine was started, you almost certainly need a new pump. And very likely the broken rotor ground up a lot of metal in the pump. Since the pump is after the filter, this ground up metal will be distributed throughout the trans and can cut seals and clog valves.
So, if there is evidence of ground up metal, not only does the entire trans need to be rebuilt and thoroughly cleaned, but the converter needs to opened too for a thoroughly cleaning and re-welded, the cooling lines need to be flushed and any multi-path trans cooler needs to be replaced. Otherwise the repaired trans may quickly fail too.
Sorry to give you this news.