It's still a MII based suspension. That's a lot of money to clear up some space for headers, imo.

You could buy a TTI system complete to tailpipes for less and clear your stock based suspension.

I also have to wonder about the bumpsteer. In his specific installation, there may be none. But the early A body has a different inner LCA pivot location than a later one and a generic MII rack may not have it's inner tierod pivots in the proper place. Not to mention that ackerman will vary depending on wheelbase. Sounds like some fine tuning/checking is needed to ensure proper geometry. Not to say that the stock suspension doesn't need it too.