Success!
After more than a week, success was had.
14.5° PA, 16 DP, 20 Tooth, 1.375 (1 3/8) Aluminum gear. 0.2505 ID
The number of subprojects that went into this one simple little gear boggles my mind.
Locate a reasonable rotary table
Document what was needed for it
Clean and restore 8" Cushman Chuck
Make chuck key
Locate dividing plates for the rotary table
Make T-Nuts for rotary table
Make socket-head replacement screws for chuck
Make socket-head attachment screws for chuck/backplate interface
Make backplate
Make retaining collar
Make MT3 alignment plug
Modify eccentric to have a retaining grove for U-Spring
Make grooving tool
Make nose cap for spindle
Thread eccentric for tensioning ring
Make a mandrel for holding gear blanks
Make gear blanks
Read the section in the 1914 Machinery's Handbook about gears
Create Emacs spreadsheet to calculate gear cutting parameters
Create a Python program to create a dividing plate table
Incorporate dividing plate information into Org-mode spreadsheet for single point of information (Enter DP and Number of teeth, get out cutting parameters and which dividing plate to use along with dividing plate setup)
In addition to that, I have 3 toolholders almost finished, I'm still waiting for the dovetail cutter to arrive and then to drill and tap the adjustment screw plus the retaining screws.
For those that might wonder why 14.5° PA, 16 DP instead of a more modern 20° PA, it is because this is what my lathe uses. With a single purchase of the 8 involute cutters, I can make any gear my lathe might need.