First of all English is not my native language so I apologize if the question seems somewhat simple.
Reading through A Complete Collection of State-Trials, and Proceedings upon High-Treason, and Other Crimes and Misdemeanours; from the Reign of King Richard II to the End of the Reign of King George I and especially the part regarding the pirate Henry Every we can see the famous quote of his:
"I am a Man of Fortune, and must seek my Fortune."
However, nearly all the modern versions of this exact same quote are rephrased slightly:
"I am a Man of Fortune, and I must seek my Fortune."
No doubt the original text has been valid at the time of the writing, but that was nearly 300 years ago. The question is whether it would still be 100% grammatically correct sentence in today's English if the second "I" is forfeited? I wouldn't know if the rephrasing has grammatical or aesthetic reasoning behind it.