1983 Chevy Malibu Return on Investment

Hello, I've read sometimes conflicting web articles and opinions that the low end performance and fuel mileage on my well cared for Malibu wagon can be greatly improved with a better camshaft and roller tip rockers. The total cost would be about $600 after figuring misc. Expenses. I've already fabricated a dual snorkel air filter hsg. With K&N element and plan to modify the exhaust system but am not building a hot rod. Are these parts a worthwhile investment and are there disadvantages such as decreased engine longevity or "other"? Thanks.