Well, I'm certainly no guru, but here is what I would try. It looks like there are several shims. Maybe try them half on one end of the spring and half on the other or some different combos more on one end and one on the other, if they fit in that way. Turn the spring over and do the shim shuffle that way.
You will be real good at pulling and installing the cover. Plus it is way easier than goofing with the 2004r governor and its springs.
Is there a replacement spring you can get that doesn't require the shims? Maybe do a little porting of the exhaust so it can exit easier. Nothing drastic, just a clean up.