No need for you to think you're being confrontational. We LOVE discussing things like this!! It's what we live for!
And to continue the discussion, there are a lot of WEB sites that show the JM code for the 1969 Nova, and while it "may" exist, none are known to have ever been built.
We at the CRG use original Chevrolet documentation for research because books, magazines and WEB sites are usually (more often than not) riddled with errors. The example below was taken from the September, 1968 Parts and Accessories Manual (P&A 25) showing what the engine codes were for each Chevrolet model in 1969. As you can see, there's no JM code listed for the 1969 Nova. However, while I never say never, without hard proof, I'm a disbeliever.
But even GM docs can be contradicting so we use several different GM resources to verify what actually happened at the time of manufacturer. Sometimes this can be really frustrating but usually, through a lot of digging, we can get to the truth! A good example of this frustration is the Dual Disk clutch option for the 1969 Camaro, RPO MA6). There are references to it in Chevrolet records, but again, none are known to have ever been built. The 1969 Corvette, yes (102 units), but not the 1969 Camaro.
If you have an original GM doc showing something different, please let us know. We're ALWAYS on the lookout for original GM documentation!
Ed