I'm in the same boat as you, but have all the bits except the thermostat. Contacted awesome powdercoat before and you are right the shipping is very expensive.
I've managed to source the flaps locally. The flap mechanism for the the doghouse and non-doghouse are identical so try and post a WTB ad for those on the Facebook platforms. The rear linkage is however different between the two. I should have a drawing of the difference somewhere.
The thermostat to linkage rod should be able to be sourced from local vendors.
Here's one from ONE vendor. Search your favourite vendor for the same.
https://www.classicveedub.com.au/cvd_new/part_detail.aspx?parts_id=27322
Here's the return spring from ONE vendor. Search your favourite vendor for the same.
https://www.classicveedub.com.au/cvd_new/part_detail.aspx?parts_id=27323
The bracket is here, but expensive. I think you can find it locally or second hand easily. Getting the part number makes the search easier.
https://www.heritagepartscentre.com/au/043119151-thermostat-bracket-1200-1600cc.html
Also the spring clips that hold the rear cross linkage to the flaps. Also the same as the accelerator pedal spring.
https://www.heritagepartscentre.com/au/211259283-accelerator-pedal-linkage-spring.html
So you are missing then the flap linkages and these depend on whether you have doghouse or non-doghouse and the thermostat.