Ann: Musgrave Hits 11m @ 54.0g/t at Break of Day, page-17

Yes this is just hypothetical as we do not know the actual costs and are just pulling them out of thin air
Probably would need to make the straight decline go about 2o meters under the top of any economic ore as if open hole down hole stoping would need two sub levels to work from and to then muck out the ore from the lower of the two stopes and then cork screw a decline down from the lower level to access horizontal drives deeper down . I imagine I have underestimated decline and other costs too much as the likes of Andy well and Wattle Dam had mining halted due to development costs per ounce when there seemed to be still considerable ounces per vertical meter below where mining stopped .