I don't think the stock housing can be easily modified.

You could run a 3.07 geared Dana 61 rear.

You could also try a used set of 2.47-2.76 gears in a Nodular 9" casting with Daytona pinion support and 35 spline Detroit Locker or spool. I don't know how the 28 spline pinion would hold up, however.