I have the power rack but believes it mounts the same.
First question, are you saying you don't have enough vertical adjustment on the inboard brackets(that bolt to the lower control arm bolt)?
On my car, I did not see the shims "aligning" anything. The only purpose I can see the shims making is lowering the rack for header/oil pan clearance.
Basically, set you outboard clamps first. The outboard mounting points are basically fixed points because the mount directly to the frame rails, therefore they are the points that physically locate the rack horizontally and vertically. Once the rack is located, you just slide the inboard clamps in place.
To do this,
Bolt your inner brackets in loosely through the lower control arm bolts and leave them loose enough so you can move them up and down through the slot on them.
Put 1 of the shims on the passenger side outer most bracket.
Put the same size shim on the driver side outermost bracket(on the power rack this is a fixed bracket welded to rack) and snug up the bolt.
Back to the passenger side outboard bracket, snug up the color that clamps it. Ensure even gap on bother sides of the clamp.
With the outboard brackets snugged in place, the rack is now physically located into the place it wants to be.
No for the inboards. With the control arm bolts loose, First, snug up the clamp evenly. Once the clamp is snugged up, you can snug up the lower control arm bolt.
If you were setting your inboard clamps first, its damn near impossible to get the outboards to line up.
Also, I recommend putting BLUE loctite on the clamp bolts. Mine would work there way loose every now and then. Loctite fixed that.
