About central air conditioner?

Heat pumps do very well in Southern California. The only things you really need to weigh are 1. The initial installation cost, and 2. The price difference in paying for the electric to run the heat pump, or the gas to run the furnace. That just requires a little homework. Either way, you'll get a very efficient unit compared to your 30 year old antique. P.S. check with the Gas & Electric companies in your area for possible rebates. That might also factor in to your decision. Good luck.