I have 2 of these KAL 2969 spark analyzers and have found them useful.

https://www.ebay.com/itm/3052253888...DjXYqPdGJ2AlKLQNy%7Ctkp%3ABk9SR8DckcvvYg

They clip around a ignition wire and give continuous digital readouts for an individual cylinder of:

peak kilovolts (what it takes to jump the gap and begin the spark)

burn kilovolts ( lesser amount of kilovolts to continue the spark)

burn time (thousandths of a second the spark endures)

These numbers can be used to tell whether a cylinder mixture is rich or lean,
and whether compression in that cylinder is good or poor.

Such a meter and readouts might be useful on a lean burn system

I am attaching two photos from the KAL 2969 manual pages that explain this ( hope they are in focus good enough to read)