Spark plug reach

This question is why we need to go back to about 1970, 1980, 1990 and if not paper catalogues with actual information, then the electronic versions thereof.

This sort of thing, here

https://www.championpowersports.eu/assets/II-Partnumbering-structure.pdf

In Champion speak, "J" as in J-12Y is a 3/8" reach plug, H is 1/2, N is 3/4 like small block Y is extended insulator, so a J-8 is still 3/8 reach but the insulator doesn't stick in as far, and adding an R to the front means resistor, a C to the rear means Copper

They make a CJ-*** which is "compact" for power equipment, it is then 3/8 reach but "compact" meaning smaller (3/4?) hex and short insulator. There are other combos, which is why, in this day and age, we need damn catalogues!!!

Only thing I can suggest is search around for other brands of catalogues and when / if you get a number and confirm "it is good" then interchange that to a brand you really want