All GM OEM point coils are designed to run on 7-8 volts; replacement parts store coils (like "Standard", etc.) that require a resistor for reduced current normally are stamped "requires external resistor" or something similar. If you have either of these two types and are running it on a full 12 volts, you'd better carry a spare coil, because 12 volts WILL eventually fry them. Aftermarket performance coils are another issue - some are designed for a full 12 volts, and some aren't - go with the manufacturer's instructions. I've been at this for 40 years, and I've replaced lots of fried stock coils that people thought would run "better" with a full 12 volts on them; they don't.