4.10's would be the minimal gear for the viper spec'd t56.... but based on the rpms numbers above, it seems 4.30's to be the best choice since you won't lose you cruising abilities.
"A buddy of mine has a Viper Spec T56 and runs 4.30's with a KB at 14lbs of boost. It's a good choice. However, he needs 5th gear close to the end of the 1/4 mile. A 28" slick cured that problem."
I would lean towards the 4.10's then, only so you wouldn't have to worry about the extra shift assuming you are going to run that kind of boost. It all really depends on your future plans. Are you happy with where your car is at with the current power levels (or when you get the KB stay at around 10lbs)? If you are truthfully planning for big power, you need to worry about the shift points. If you are going to stay say at 10lbs, then 4.30's will still allow you to only go through 4th at the track. You just got to take a step back and figure out what your power goals are....and don't make the mistake most peeps make in terms of dreaming of where they want to be, rather than were they can only get. That's one of the main reasons I still have the stock pulley on the s-trim....b/c I know I won't have the funds (have a house now) to get a built block and would rather give up power for reliability.