Favorite gear ratio for street car

My 68 GTS, 340 4 Speed, 284/484, 10.5 cr, headers, LD340 and holley 3310-2 carb, MSD-5C. I ran a 4:30 gear with G70-14 tires.

The car now has stock intake and manifolds, same cam and AVS and I’m going from the stock 3.23 gears to 3.91’s. I feel a 3.91 is the best 340/4speed gear.

Cliff Ramsdell