Carburetor size Question

A 275 tire (w/3.23’s) would be 2189 rpm @ 55 mph.
Leaning toward a 275/60-15 with 3.23’s.
This above is correct?
But do you travel this speed as a norm?
Do you travel the interstate?
What is the normal interstate speed and at what rpm would that be for this combo?
What would it be for 70/75 mph?

I’m curious. So far, for the elevated speeds, I’m mentally guesstimating the rpm may fall into the cams sweet spot where it is really more efficient.

Thanks