I ran a D200 PU back in the day. All over the place with a lot of highway miles. 4.10's and 29" tires. It did OK on the highway. I would cruise 70 and sometimes 75 max. It was probably turning 3300-3500 RPM on a sustained basis at higher speed. That is as much as I would want to run and even then noisy even with turbo mufflers.

With car size tires (25-26"?) I think 3.91 would be too much. Also speeds are higher now.

My current classic PU runs 4.10's and 31" tires. OK to 70-75 MPH and spinning pretty well at that speed. As much as I want.

My '70 Challenger ran a 318 and 3.23 as original with 24-25" tires. The original powertrain did surprisingly well. Decent acceleration and OK on the highway. Now runs a 496 and still 3.23 rear. Also OD transmission. It runs well.

If highway driving is part of your plan, I would suggest a 3.23 rear. It will do fine on the highway and the 383 should handle it fine at low speeds. Plenty of go.