OK, here's what I've learned, so far:
I found the modification, that Rick mentioned, on the Internet.
(See Chapter 4 in this article:
http://www.joesfalcon.com/page14.html) The article says this will lower the front 1" and put the suspension in a better handling mode. A lower front spring will lower it further, but to be safe, cut a little off at a time, or buy a lowering spring.
Apparently, Shelby figured this out and was the first to do the upper arm repositioning, that Rick mentioned. I read that he built 3 Shelby Rancheros, in '65. One is supposedly up for auction with a reserve price of over $200,000!
Looks like I got a real deal when I bought mine!