Noah,
Please re-tune your car. Way back when - 5,000 miles was a good time to, as a matter of fact most guys retinkered/timed their cars every month or so in their driveways to keep them running optimally. I know your plugs will last 10,000 or more but points aren't what they used to be and one other thing to check is your vacume advance (if you have one) is it pulling or leaking? Good Luck. Our Flat Heads like to be advanced on the timing 4-6 Degrees as well from the static timing position. Here is wishing you - Happy Wrench Turning.
Tom