As the owner of a car with a cammed 440 and a .68 OD ratio with a 4.10 dana, my perspective is I still don't have enough gear to make effective use of OD until I'm going 70mph. Of course it screams in 4th gear at 65. The tremec gear splits don't work great with cammed up street cars IMO, 1st gear is already granny gear, if I put any more gear in it I'd never use first, less gear and I'd only use OD when I can go 80 on the freeway. If you go with a 3.55 I don't think you'd often find yourself in 5th gear.