1976 Cadillac EL Dorado battery

What kind of problem are you trying to solve? 1000 cold cranking amps will start a diesel pickup truck engine. You don't need that much to start your engine. A standard battery will be fine. It's easy to find them with around 750 to 800 cold cranking amps. That is usually significantly more than what the car came with originally. Once you find a battery that is the right size physically and at least as big electrically as the original one, don't waste your money on gimmicks you don't need. If the Optima battery you're considering meets the needs and the price is close to that of other batteries, it doesn't hurt to have higher cold cranking amps. That doesn't mean the engine will crank faster. It just means the battery's power will not fall of as fast in cold weather. It will have a higher capacity, but that extra capacity won't be used most of the time.