I had the same dilemma when I purchased our Chevelle. Only 20K miles, but the engine compartment looked pretty crappy....and it did not have the benefit of being a California car. It had been driven (albeit sparingly) for several years in Northern IL, year-round, and then had 29 years of less-than-ideal storage conditions
. But once you start, where do you stop? Get the engine compartment looking spiffy and then all of a sudden the chassis doesn't look so good any more. Do that, and then you start 'finding' all sorts of flaws in the paint, and on and on it goes. Like others have said, do a little gentle cleaning, drive it and enjoy it.