Koni Reds are actually adjustable. The thing is you have to take em apart to get at the adjuster. They're a pretty good shock and should stand up to the load placed on them by say, GCs or something. Another option for a beefy non-adjustable shock is the Bilstein HD. They're kind of hard to find though.
I wouldn't bet on it by much. They certainly won't be overworked by the Prokits and the fact is that they're a pretty aggressive shock.

If you want a softer ride I would look at the more standard Koni offerings, or just live with the ride of the Neuspeeds and enjoy their handling abilities.