Payback Question

Was looking at the last presentation`s slide p.11, produced this fall, which lists the payback, as per the PEA, at 2.8 years at POG $ 2,665. They also list that payback would be 1.6 years using POG of 3,700 as it was traded last fall using the same parameters as used on the PEA. Note that the NPV would jumped to $ 388 M to $1.25 B AUD.
Now, POG is 4,700 I would assume that the payback would be close to one year and the NPV would be an obscene amount especially considering the current market cap.
Was a bit surprised, however, to hear the CEO mentioning a Payback of a couple of years when he was mentioning 300 M annual free cash flows versus capital cost of 350 M. Conservative for sure. They also seem to be cautious with the PFS, taking their sweet time or so it appears.
Anyway, found this company through their Dundee ownership. Goodman and his team do very thorough reviews and do have a couple of homeruns in the last years. This decrease the risk materially, at least in my view, so bought a few shares.
GLTA