Mike, and as you know, 3500rpm is nothing for a small block Chev. Smart move though to "go easy" on it. Still, foot to the floor, it "could" have done the hill faster. But what's the hurry....is it a race ? Not really.
230 degrees, yes, for many years GM has decided that "running them warm" is routine. Even back in the 80's, they like to run their car engines at 210 or so in everyday use. Likely to get cleaner emissions and better economy.
Nissan on the other hand, still likes to run them below 200. My Frontier runs at 193 to 198, towing or not. (as reported by the scangage, which is always the truck )
They all work and last a long time.
The six speed GM trucks have a little bit of an advantage over the four speeds for towing.
