if you want to remove more weight remove the A/C evaporator. from under the dash.
If you remove the ducts, fan and the heater core you will no longer have a defrost mode and will not be street legal at least here in CT.
under the hood remove the A/C condenser, receiver dryer, compressor and all the associated hoses.
that should shed a few pounds not to mention help gain a few HP from lost weight and no longer running the A/C compresor pully. Also by eliminating th evaporator mounted in fron of the radiator it may help improve airflow through the radiator for better cooling.
If you do this do us all a favor and have the A/C system properly evacuated, don't just cut a line and let the refrigerant out. Although it is R134a (desn't hurt ozone) it still is a good idea to have it done properly.