[Excaliber]

3:31 is a typical Jag IRS rear gear selection, something in that range for a 9" should be available. It's what I run with my top loader and find it pretty much perfect all around. My motor, like yours, makes a LOT of torque, the higher rear gear is not a problem.

You probably have the more common "wide ratio" top loader. 1st gear ratio in these transmissions is lower than mine which is a close ratio. I shift into 2nd at about 60 mph. I would figure 50 or so with a wide ratio and the 3:31 rear gear.