Engineering
It will not be possible to exactly rebuild house Muschamp as it was built originally.
Main issue is that the original built does not comply structurally to modern NZ standards.
Moreover Oamaru stones got damaged and all interior blocks were painted.
The house was not insulated and if not heated properly, the thermal mass of the stones will turn the house into a very cold place in winter.
The plan is to develop a rebuild strategy addressing structural strengthening, building physics and appropriate building services.
The house is going to be rebuild by myself, hopefully somewhere in rural area.
The rebuild strategy has to allow for it to be build by one man as much as possible.
The rebuild is not going to work if heavy and expensive equipment needs to be brought in at a regular base.
At every step of the engineering I consider the fact whether I can built it myself.
Architecture:
The house does not allow for a lot of changes in the plan due to the rebuild of three facades, the reuse of the tin pressed ceilings and the ceiling/roof structure.
I've been looking into plan alternatives and actually concluded there is not much I would like to change.
Few things: (1) add a toilet to the house, (2) more natural light and (3) Living space and connection to a garden at the back.
These suggestions in plan changes will have to be incorporated into the design.

Base isolation:
Obtaining structural integrity for a stone build house with a heavy roof is a bit of a challenge at this day and time in earthquake prone New Zealand.
I sympathize with the idea to avoid any fights with nature; try to allow for it.
By applying base isolation the house is (horizontally) disconnected from the ground it sits on; the earth will "slide" underneath in the event of an earthquake. Base isolation reduces the applicable forces, generated by earthquakes, drastically.