The IC (Instant Center) of any suspension system, is the point where the forces from the rearend housing, apply themselves to the chassis. Basically, a ladder bar, is like a leaf spring, but the advantage is the ladder bar will not give, plus it moves the IC forward because of bar length. This applies force to the chassis further forward, creating better leverage and increased weight transfer. If you could make your front spring segment dead stiff and move the mounting point out even with the ladder bar, it would be as good as a ladder bar. All this is why link suspensions, be it a 3 or 4 link, is far superior. You can place the IC where it NEEDS to be, to properly apply the force to the chassis, to get the results you desire........Oh, one more thing, if you followed this at all and learned anything about how suspensions work, you can also see why good SHOCKS are critical for a good working car. The whole exercise is about "controlling the housing and applying force". You can have the trickest suspension in the world, but junk shocks render it useless.
Monte
If I had talked to someone like Monte before I purchsed my Caltracs and split mono leafs, I would of bought Chevy length springs which are 5 inches longer in the front segment of the spring. This would of required a little more fabrication, but I think in my case of trying to hook up a 10.5 tire with a BB nitrous trans brake combo, it would of helped. Next step is "good" shocks, and maybe a glide($). I have to run the leafs to be legal in my heads up class, but that triangulated 4 link looks like a nice system. I hope the original poster got some helpful info from his question? I know I'm getting something out of it.
