A lot of hassle for not much gain (if any).

I had a very similar combo in a 71 Cuda and the the deep 1st gear swap along with all kinds of gears going as deep as 4.56.

In the end I really liked the 3.23 rear gearset and the standard 2.45 first gear in the 904. It was the best of both worlds (drag and street).

As an aside, I built my current '63 Dodge 330 with 3.55's because I knew it would see long runs and lots of street duty. I'd never go deeper than that on a street car with no overdrive. The 440 has more than enough torque so deep gears are not needed..