Are you sure this is a '72 serial number? It very well could be, but if it left the factory in '72, then the orange manual is incorrect as they were only used from '75-'77. So I imagine this being a factory engraved example, it probably stayed at the factory for a while, and ended up leaving between '75-'77.
The factory probably used a blued gun as the base, and never matched the sight pins to the final nickel finish. Assuming it is indeed factory, which it certainly looks like.
What I think it is worth and what someone may pay for it are two very different things. It's the same no matter who you ask.
I don't play around with the "big toys", so I have no idea what this example might fetch at auction or FTF deal.
If buying, as cheap as possible and you feel comfortable with. My comfortable range is considerably lower than most.
If selling, and the gun is truly vetted with proper documentation, the ideal thing to do would be to have a "popular" online auction dealer who targets deep pocket collectors move it for you. Normal people just don't get the money out of these guns that certain online dealers enjoy. So when it comes to a unique variation of Python, that would be the best way to go for ordinary Joe. Who to pick is up to you. I don't care for most of them, but it's how you would get the most.