How much power? And better yet, how much traction? If you're just going to run BFG T/A's then you'll probably spin before you hit that 741 super hard. If you're going to run drag radials or slicks then the 741 might not be a great idea depending on your power upgrade plans.
That 741 case probably doesn't have more than 3.23's in it too, so you definitely want to consider your gearing before you go too crazy.
While the 742 probably had a clutch style sure grip from the factory, and the 489 likely had a cone style, what you can find now is totally different. No reason you can't put a clutch style sure grip in a 489 case.
