Mission accomplished! Found two coils locally and got them installed this afternoon. Fired up the tractor and it's running on two cylinders.
The test will be tomorrow when I start mowing.

(After I sharpen the blades and clean the deck while I have it off.)
Doing the job once, I can see it wouldn't take nearly as long the second time. It's really not that big of a job. A lot of my time was spent cleaning up, re-taping wires, etc.
I was at a dealership today and checked out the new Cubs. Probably nice units but lots of plastic and $5400 to replace my set up.
Makes repairing the 1864 seem much more worthwhile!!
Thanks for the advice and suggestions.