another rear-end ratio question

[willett]

hey guys

i'm running a lifted '78 lwb with a 454, NP205, and a turbo 400 on 35's
i have 3.73's in a 14 bolt and i'm spinning about 3200 RPM at 110 km/h ( i think about 65 MPH)

if i were to throw some new hardware in my diff do y'all think 3.42 would be reasonable?

any other suggetsions?

i don't do alot of wheeling in my truck, but i am known to get her stuck in the mud on occasion