Much as I liked Frank's bonnet bumper idea, I haven't found the time to fabricate it... I have been just living with the noise. But, when one has as (ahem) GREAT sounding a car as I do, it's just a shame to have it make all that unholy racket at every stop light.
"When you have a tough project, give it to a lazy person to do. That person will find an easier way to do it."
(Source unknown to me)
I looked at it today, still thinking there has to be an easier way. I went to the hardware store thinking I might find a rubber-bottomed leveler foot of some sort, that I could use to replace the center-most bolt holding the spring assembly together. I didn't. I found a 1" rubber plug though --> a 1" dia. x 3/4" tall piece of rubber with a 5/16" hole through it. I completed the set with a 5/16" x 1-1/4" flat head bolt, a nylock nut and some washers. I countersunk the rubber plug so the flat head bolt would go into it well below it's surface (total fabrication time: about 1-1/2 minutes, including finding the right countersink). I took this out to the car and used it to replace the bolt I mentioned before. Height adjustment is accomplished through the use of washers below the rubber bumper.
IT WORKS!