Getting good spark and a precise tune is step one for making any engine run better, but doing it with worn-out parts isn't going to get you there. Upgrading all the external components like coil, wires, and plugs is a start, but to keep your engine firing precisely, the internals of the distributor need to be in tip-top shape as well.
Replacement aftermarket distributors run the price gamut from the ultra cheap with questionable quality, to high end and pricey for guys making big power. But if you're on a budget, there is another option-you can keep your vintage HEI, and just upgrade the internals with affordable and effective mods to make it hot rod ready.
Usually considered the father of all modern ignition systems, GM's venerable HEI ignition made its initial appearance in a few '74 models, but became standard equipment by the following year. One of the main breakthroughs that put HEI miles ahead of previous points-style systems was its then-revolutionary expanding dwell circuit, which increased the amount of saturation time experienced by the secondary side of the coil as rpm increased. That concept brought in more power where it was needed most; under high rpm and load. Plus, without troublesome points to wear, the current carrying capacity, voltage, and spark duration all went up while the required coil charge time decreased. That's why to this day, HEI remains a staple for any hot street/strip engine that makes all its beans under 6,500 rpm.
Nowadays, the ignition evolution continues with strong aftermarket support that has made rebuilding and upgrading HEIs a quick and easy project that just about any rodder can bang out in a couple hours or less-even if you're a perfectionist who takes the time to detail the housing.