Of course you're right about this point. It's just that the bulk of the MMP book has photos of the restoration of the Mustang which is now painted as "Happy Jack's Go Buggy" (airframe is 44-74452/RCAF 9225). This restoration is remarkable, even down to the Alclad watermarks showing through the zinc chromate in the wheelwells. It may not be perfect but very close and I think for the purposes of building a model it's a great reference.
The P-51SIG website is amazing and will give you access to a huge pool of resources.