What type of gas do I use in a 1966 Mustang with 289 4bbl?

That's a fish I caught in a river in Central Calif in case anybody was wondering,,,no idea what is is except the obvious: a fish

t'shoes I don't know your age, but dude..those were the days indeed. I for a short time had a '65 Mustang 289 and being young and dumb, actually 17 at the time I sold it for (obscenity omitted) $500 because it was loosing coolant that I later learned what a freeze plug is. A 50¢ freeze plug. It was not the ultimate 1964 -1/2 Mustang but a '65 that hit the Ford Dealer Showroom in October 1964 with a 289 w/4bbl & manual 4 speed..that dang car weighed about 2000lbs and would light up tires literally into flame. Okay...taylor...the best gas you can find. NO OFF BRANDS..91 minimum...and if you have a small airport in your area they will be happy to take $6 a gallon for 101 or maybe even 103 octane. Sometimes they will 'hem and haw' aaack you want what? But just tell them and rest assured they will take your money. The 101octane gasoline has an extremely high flash point. Your 289 probably has an 11:1 compression ratio, the 5.0 for that year does, early version of the best engine Ford ever produced... to this day. It's no fluke these engines have lasted so long in production and performance.

Good evening davidh25. I was wondering but was afraid to ask. Lol