Ann: Drilling hits visible gold over 1km deep below Never Never, page-64

I am no UG mining engineer , but if you were to put a decline down , would you not want to do what SL has done and drill a couple of deep arse holes so know the approximate workable depth of the ore body first so that would be part of mine planning plus the proximity of the decline to other ore bodies like WW and the pillars ?
Then you can put a straight decline on a 10% angle downward first to the midway point vertically below the NN crown pillar and the deepest mineralisation , then put in a T intersection with a spiral decline up and a spiral decline down so you can double the production from 2 headings.
Would also have to save quite a bit of tire wear and rim pull than going around in a spiral up and down.

as for infill drilling I would leave to later and be fan drilling from a plat down the decline like Beument did at Paulsens into Voyager 1 and 2 , (unlike the previous idiots who drilled from surface ) to reduce both cost and drill deflection , and only relatively wide drill spacings would be needed anyway due the current wide intercepts

Just my thoughts and no mining pro experience so could well be wrong