A long time ago, I think someone posted that they found a Mercedes that used a 3.55:1 gear ratio, but whether or not it was the same "type" differential the Crosssfire used was not made clear.
Nobody, produces a "lower" gear ratio "ring and pinion" for this style differential any longer.
And no, Crossfire's don't come with LSD, not even the SRT. But an aftermarket unit is available.
Tealcamaro55, I use to have a 94 Z-28, 6 spd. "chipped" so I have a pretty good idea of what kind of performance you're accustomed to.
So unless you're going to be content with having a car that's probably (at least) 2 seconds slower in the 1/4 mile, than your Camaro, then you may want to consider a SRT.