Since some of this would involve plastic chrome I'd probably talk to these guys in SA.
http://www.aclassmetal.com.au/
Otherwise I'd probably Google search for companies that specialise in this sort of work.
http://www.vaughtons.com/refurbishment-repairs/
https://www.mastercast.com.au/custom-car-badges-mastercast
But I suspect a lot of these guys don't really have a website.
EG:
http://www.fbekholden.com/forum/viewtopic.php?t=15187
And things you learn about badges.
https://www.smh.com.au/money/investing/badge-to-the-bone-20100524-w662.html
I've still got these if you need some?
You may want to also consider these..
https://jdm-car-parts.com/collections/emblem-decal-sticker-nissan-datsun-fairlady-z-240z-260z-280z-280zx/products/datsun-260z-fender-emblem-set-nos
I sold a set like these not long ago, for considerably less than that, but still $$$.
And then there is these..
https://jdm-car-parts.com/products/quarter-panel-emblem-260z-280z-2-2-nos?_pos=5&_sid=3598b5b91&_ss=r
Some other discussions here:
Said reproductions existed here:
https://zcardepot.com/collections/260z
*Edit, found it..
https://zcardepot.com/products/fender-emblem-260z?_pos=1&_sid=88d5c99dc&_ss=r
Appears they are smaller...