You may find that new hoses will fix the problem. Though R&R of all components is a good idea if you don’t know the history. I believe the original ATE parts are best quality, at least for wheel cylinders. I had some ATE and some aftermarket (FTE?) and remember thinking the ATE were better constructed, though I don’t remember the difference. BTW those brake parts can all be rebuilt with new genuine seals and pistons as long as they’re clean inside.
If NZ prices are like AUS it would be cheaper to import, notwithstanding the import taxes. George at Authentic Classics is a reliable source. It would be worth checking his site for what you need.