Racers look here to help a newbie -Thanks
I tend to disagree with the people that say go to a four link. I would ask the O.P. if he's driven a dedicated race car with that style of suspension or a trans brake? I'm gonna say that the learning curve would be fairly steep compared to stepping in to a leaf spring/footbrake type car.
The Calvert stuff is proven into the low nines. If you're going that far, there's going to be a lot more considerations beyond rear suspension so at that point its going to be an entirely different car anyway. I guess he has to answer what he thinks his immediate and future goals are with the car.
Again, the Calvert stuff is $1,000 but that's it. There's generally no fabrication involved unless you move your springs inward, but that's minimal compared to the work involved with putting in a 4 link. 4 link kits range anywhere from 6-900 for raw materials alone. It then has to be welded in by someone competent and those guys are not cheap. There's a cage involved with both setups but it would be a lot simpler to deal with with a stock style setup. A 4 link is likely going to be tubbed out so you're looking at tin work too. And oh yeah, are you going to run a a stock front end with a 4 link? Probably not! (more $$)
Learn to drive at that level and figure out what the car does with a basic setup before you start going crazy with all this stuff. Even if it is a dedicated race car it does not have to be complicated.
If you read the M.W. 4 link kit description, it says there can be 144 different instant centers. I think more than one could make your head spin.