You are almost correct regarding the capex increase, up by...

You are almost correct regarding the capex increase, up by 2.36x,
but both the 2019 and 2024 capex are for a 2mt plant

This remains highly profitable despite the capex increase and other factors reducing the AN 2024 NPV

AN alone offers a potential triple on todays share price, less dilution
and the full projects together offer 10x, on NPV vs current Market Cap, funded out of cashflow

at conservative product prices and ignoring the prospective much longer resource life

-----

For opex, they've used tenders for transport costs and it can't be too hard to cost a man with a digger at site, plus plant operating costs

2019 AN BFS post tax ungeared NPV10 $242.3m
Capex $28.26m
C1 Costs FOB Port of Geraldton $30.18
ASX announcement

2024 Updated AN BFS post tax ungeared NPV10 $166.7m (-75.6m)
Capex $66.8m (+38.5)
C1 Cost FOB Port of Geraldton $31.43
ASX announcement

Total potential upside AN+A Central+Muchea?

If I prorate the Muchea and A Central NPVs in the same ratio as the AN numbers 2019->2024
as a crude estimate

2019 NPV10 totals 242.3+147.6+337.9 = $728m
=> 2024 estimate 728*166.7/242.3 = $500m
using conservative forward prices

vs todays $51m Market Cap

Muchea 2019 post tax ungeared NPV10 $337.9m
Capex $32.82m
ASX announcement

A Central 2019 post tax ungeared NPV10 $147.6m
Capex $25.9m
ASX announcement

gearing does not change the outcome much, as previously pointed out