From the photos it appears that the rust mess has been caused by two factors. First is brake fluid leak which seems to have been massive and second is debris accumulated on the bulk head area. Brake fluid is a massively corrosive fluid which in combination with moisture trapped on the debris has accelerated corrosion. Funny enough I had this job done on my 33 last summer.
The amount of rust was just on the surface but if left untreated it would be a nightmare. If you want a proper job done you need to remove the AC box and the battery tray plus all wiring. There is no need to remove the wiring entirely but you may simply put it out of the way so that the boy shop is able to spray new paint.
You have almost done 33% of the job by removing the hydraulics. From the photos I see that you will need the pedals box and pedals blasted and powder coated, new plastic bushes for the pedal shafts, new master cylinders, and have the steering column frame remove if you want to paint it also. It is a matter of how long you want to go and how much detail to do. For sure where metal has rusted through, it will need welding. The amount of rust is too big to rely on rust converters ... rust will come back for sure, so better do it once and for all to have the bulkhead completely empty and a body shop treat the bulkhead properly.
In my case, dismantling took me 3 days, the body shop around a week and reassembly around 1 week. More or less around 20 days working on the afternoons.