I live in No Va too. My old 2002 was stock and I could get away with 87. But 89 will work good without any knocking or pinging. I did happen to notice around the area that some gas stations have cheaper type gas. I don't know what it was but I could feel the car run differently with other brands of gas.(don't ask me) But you should run the best gas in the winter around here and throw in some gas dryer during the cold months if you do alot of highway driving. I used to have my carbs freeze during highway driving. I would stall on the road and I would have to wait until the heat of the engine melted my carbs. If you have the K&N filter you might experience it.
I have a stock 76 02 with Webber 32/36, no smog, live in No. VA. What grade of gas should I be using? Forgot to ask PO when I bought it and haven't had to refuel yet.