I've never really seen B-series engines swapped with auto transmissions. Something tells me there'd need to be some custom work done on the ECU used. My best advice is to sell your car and purchase a 5-speed. While it does sound like a big step, converting to a 5-speed can sometimes be a costly and unwise modification to make. Another option is to purchase a cooler for your transmission and a torque convertor.

Still, if you are looking to remain an automatic, have your LS engine outfitted for some heavy boost and turbo your car.