New to mopars and needing help

Whats up everyone my name is brandon and i just purchased a '68 Coronet station wagon with a pretty hot 440 in it. i have never worked on mopars before and i need some advice. i know its kinda dumb to buy a car without knowledge of what im workin with, but its a tubbed pro street car that i got a nice deal on so i couldnt pass it up. im tryin to find out how much timing to run so that i can use 90 octane pump gas. anyone have ideas where to start?