Rear end gear question? 3:23's OK

With a 408 i think you could use a 2.94.
I have a stock 340 and am looking for 2.94's to try in my Dart.
..Anybody have experience with 2.94's?
experience with a 400hp 360... went from 3.91 to 2.94 rear, the 2.94 is way friendlier for cruising but it was significantly more fun with the 3.91... I will likely settle in at 3.23