Voltage drop with when ignition on

First Car 75 Duster said
when I found that wires that are supposed to be 12v or now at 9.8. Que a storm of the loudest f-bomb I can muster. I have no idea what my next move should be

what wires did you use? (Where the 9.8v is)

If you took off after the ballast resister that could be the reason for 9.8.