Thank you Sundog! About the Miles M.20, you may very well be correct!
The currently available Warbirdsim P-51B/C's for FSX are fully native as they stand right now, but they are quite a bit aged, and have been under the knife, on and off, for quite some time, for an eventual full-upgraded version. I can say that there was a signficant purchase made on my part, about a week ago, that will definitely help see this upgrading through to completion much faster. Also, as you might think, there is so much P-51B/C in the P-51D-5-NA cockpit, that a good portion of the cockpit of the P-51B/C can be upgraded by simply using what exists in the cockpit of the P-51D-5-NA. However, the challenging part comes down to items like the windscreen/canopy enclosure assemblies, and entirely different gear wells and wing-to-fuselage fillets. I can say that the future looks bright for high-back Mustangs in general - though that future is still quite a bit of ways away, with other aircraft on the bench as well.
I'm glad you like my story-telling! ; )