Well, it worked. Starting from a contact print exposure, and noting the negative stage height and lens aperture, I put the negative into the carrier, then raised the head to enlarge to my desired image. Noting the height change of the negative carrier, and considering the enlarger lens was opened one stop, I calculated the exposure.

The result was spot on. Another way to say it is, the results are acceptable to me at this stage of my reentry to the darkroom. There are plenty of boo-boos in the final print, but I was able to get done what I wanted to get done, using basic exposure calculations from a contact print. I will use this basic method to get print exposures in the right ball park.