[hemi43]

First of all, congrats on using those angled shims. It's probably the biggest improvement you can make (anti-sway bar comes second) for stability, IMHO.
As far as the locating bolt; It's nice to have to line up the springs, but not totally necessary. Once the U bolts are tightened down, that locating bolt does nothing.
Assemble everything finger tight, and check your wheel base with a tape measure while snugging up the U bolts. You want both sides the same (assuming your rear axle is in the proper location).
If you want, you can stack a few washers under the head of the locating bolt and the grind the washers down to the same diameter then install.
I made my own shims and bolted them right to the springs like Richard was talking about. Funny part was that I had to elongate the hole in the spring perch 1/8" anyway because I couldn't get my wheelbase equal on both sides.
Please post back and let us know what you think of the extra caster.
FWIW, I'm running around 6-6.5 degrees of caster.