I guess it depends upon what one calls correct. I have many pics of original Colt 1851 pistols that show different backstrap/grip profiles, depending upon whether it was a 1st, 2nd, 3rd, or 4th model Hartford, or a London model of different variations.
I challenge any here to produce a "true" 1851 grip frame profile based upon historical writings. One might refer to the illustrations in Nathan L. Swayze's " '51 Colt Navies" and take a peek. That book is considered a great reference insofar a the original Colt 1851 Navy is concerned.
There are even more profound differences between the various Dragoon models. Colt changed things with his pistols as he saw fit as a business venture. He did not worry about what we would perceive 150 years into the future.
If you venture into the realm of the 1848/1849 Pocket pistols, you will realize that during the changeover between models that Colt wasted not a single part insofar as producing any pistols that would sell on the market, regardless of whether it fit our modern day effort trying to categorize which pistol is correct or incorrect. For more concise information about these little guys, I recommend obtaining a copy of P.L. Shumaker's excellent treatise. It is definitely an eye-opener insofar as parts usage at the Colt factory.
I guess it is what ever trips your trigger...
Jim