Just in from the shop. After building my tool as described above, I rolled the car forward 3' and measured the tire separation 6" off the floor at a conveniently located rib on the sidewall near the tread. The front and rear measurements on my ruler index read 10 1/4" and 10 5/16", respectively, producing the 1/16" toe in as specified. That's after having the entire steering control system apart, replacing the tie rod, installing an EZ steer kit in the tie rod and drag link ends, and setting the tie rod end spacing by eye using the old one as a reference. It is better to be lucky than good - at least now and then! As we got lucky and had a chilly night here in Massachusetts, the roads were dry enough for a test drive. Seemed to steer pretty much as expected - though perhaps not as easily as promised by the makers of the EZ steer kit.
Thanks again for all the help.