355's to 391's how much does it help?

My daily is stock 73 340 dart sport, 3.23 2800 rpm 70 mph 1/4 14s spinning, fun car and drive it anywhere. 3.91s in my other dart, local driver and drags TNT, runs 12.5 and a blast to drive!
Pick your rear gear and tire diameter to match your cams upper power band crossing the stripe.

First and second seem good, third is where I can use more.
I have to hit forth just before the finish line. And if that's the case, could 391's, 411's, or 456's hurt?