Ann: Dalgaranga Gold Project - Mineral Resource Estimate Update, page-198

regarding development cost are there two main parts to the development cost apart from capex for processing ) being the cost of the decline and the other development cost of developing the levels .

Maybe have a look at the mine plan map for NN where the decline goes closely past all the ore bodies pepper , West Winds and then look at the current number of declines BGL has and the disassociated lodes , to me it seems SPR has a clear advantage here

Still yes as you infer and as an amateur I would agree , maybe developing at up to two levels below where they are stoping out (to keep development ahead of mining ) will mean there is considerable development cost for developing the levels , before mining begins .
Couple that with the long strike lengths per level for NN , that although great once established as give a high OVM (coupled with thickness of the ore body and high grade) also means if retreat mining long hole stoping , and back filling , the total length of drive has to be developed before being mined out which will cost more than a shorter strike lengthed ore body .
Maybe one advantage is they could access the drives at a point between Pepper and NN and run them out from there so just one side is developed initially ?
IE first mine NN and then come back and mine PP from the same access point from the decline ?