A833 4-Speed on a 4-500hp 440: 18 or 23 Spline Necessary?

Just need to be clear, I need to know what will work.

Will be going in a street car, nothing crazy but I eventually would like to get the motor into the 4-500hp range.

I know there are 2 different types of cases, aluminum and cast.

I know 23 Spline came on most everything except 440/Hemis, which had the 18 Spline.

Will a 23 Spline hold up to the abuse? And is there really that much of a difference between cast and aluminum cases?