Is this a drag race or street/strip car? I use Speedway Engineering housings, but thats more suited to circle/road race. If your going custom 9", I'd go full floater. Multiple advantages such as the axle shaft doesn't carry any vehicle weight, brake pad knock back is eliminated, etc... 31 spline would be more than enough for your power level, but I'd opt for 35 to have some cushion, albeit at a weight penalty over the 31. As far as center sections, I use the iron Strange pro case (big bore for 35 spline). Aluminum cases move around a lot and eat up gears on road race/circle track applications. Same for the pinion support, iron Daytona. Differential wise, the Strange unit is almost identical to the Wavetrac, except the Wavetrac has a lifetime warranty. I chose the Wavetrac, in part due to warranty.