What gears with OD A-833?

Running an overdrive A-833 in my Duster with warm 318. There is a 3.21 sure grip setup in the 8.25 rear with 255/60/15 tires. The first gear is pretty decent in the trans and pulls nice. Cruises at 2000 rpm at 72mph. Should I move up to 3.91s or stay where I am at? I do plenty of highway driving in the LA area to cruise nights and what not. Not unhappy with performance, just thinking if I should change things up or not to get a little more acceleration out of it.