Ford 9" rear ratio discussion

[randy]

67 camaro , ls3 447rwhp, t56 magnum 2.66 , 315/30/18 rear tire (25.44") Ford 9inch

4 or 5 times a year autocross, weekend fun car

Currently have 4.11s and I was thinking about switching to a 3.70 or 3.90 gear. 4.11 are a blast but I would like to lower the highway rpms down slightly but don't want to lose to much of my 2nd and 3rd gear around town pulls. Not alot yoy can do in 1st and 2nd gear goes by quick .

What do you suggest? Will I notice a difference with going to a 3.90 or should I drop down to 3.70s?