3.31 or 3.55

Considering you say you have an extra 3rd member for racing and with that much power and 27" tires if you are really serious about wanting good cruising spirits go with the 3.31's. I have 3.55's in my car with 28" tires and it runs 2800 at 60 mph so yours with the shorter tire would be nearly identical. Just right for cruising IMO.