Walt,
I went about it in a little different way. I borrowed an Astro Servo tester from a friend (later I bought one), and it is calibrated from 1 to 2 ms. Originally I checked out the width with a scope at work to verify the calibration was correct. Then I hooked up the Astro servo tester to the Servo Test Stand (a servo mounted on a piece of plywood) I made for my JMP-2 timer. Now I marked the 1.0 to 2.0 (in 0.1 increments) on the Servo Test stand. Voila, a pulse width measurement device.
Later I discovered that by counting the throttle ticks on the JMP-2 timer (or the switch settings on the Zigras), that they perfectly agree with my servo tester, so actually you could calibrate the servo arm position with that.