If you are wanting to pull a travel trailer, I would think not less than 4.10s with the 32s. I have 3/4 ton axles with 4.10s and an sm465 in my 77. With 33s the rpms at 55mph are within a hundred or so of my 89 in fourth gear, which has 3.73s, a 5 speed and original tire size.
But then again with the 454 in the 77 I average 8mpg whether I am pulling anything or not.
