Okay, it is not quite the same as using glass lenses in one of HFT's famous 'mousetrap ' cameras and your finished product is not going to be made on salted paper but the procedure is similar and if you choose historical subjects you can give yourself a feeling for the past that digital work just does not provide. Sure, computer manipulation and plug-ins will deliver the calotype look, but actually going out there and doing a very long exposure provides the experience as well.
Okay - why even think of this? Because paper negatives have a charm and an aesthetic all their own. And they are devilishly hard to achieve with conventional camera gear - even if you have 4 x 5 or larger film holders, a wooden field camera, and that top hat. Perth's bright sun can overpower most camera lenses looking in on standard photographic paper, even if the aperture is down to f:22. You need to be able to get extremely small apertures - f:248 for instance - to allow you sufficient time to open and close a shutter by manual means.
The exposure ISO of the paper is about .6. The calcu-later will let you translate this into a time, but realyy, give it a bit more time. If you have access to a sunny photospot nearb your darkroom you can profitably experiment to see just how long you need shoot to give a good negative.
The heading image is a paper neg of Perth from Heathcote taken some years ago with a conventinal lensed camera. I will try the same view with the Obscura and see what the results are like.