8 3/4 gears

3.91 gear is 2,[email protected]. That isn't anything extreme, and a taller tire would cut that down even more. If he takes it to the track it will still be way off peak/optimal RPM, but it will still function.
You are certainly welcome to disagree, but the OP asked for opinions and I gave mine. Some of us drive more than 58mph, so at 70 or 75 he would be turning a lot more R's. I've run my 440 with 3.91's and will say that it was certainly torquey! It also drank a lot more fuel, ran hotter, and was much less enjoyable to drive. My opinions & experience!