What's the acceptable voltage range at the pos. coil terminal with points ignition?

Depends on the coil and the system used. Please post more info on setup you are using. Most all stock point GM vehicles like between 9.5 and 11.00 volts at op temp, running/coil pos terminal. They also don't like charging/line run voltages over 14.60 volts from the alternators.

Sorry, I meant fully stock. Would you add any additional resistance if upgrading to unilite.