Why not contact Mark, SCS, Oppliger or any of the trusted builders to see what they can source for you and send out, if buying an engine from abroad really is the last resort ?

At least that way you're buying from a known trusted source.

But breakers break cars....I don't think I've ever seen any who actually re-condition engines. Many might claim to sell recon engines, but often it's more like a "recon" engine pulled from a car, power washed and some paint thrown over it without actually doing any engine work at all.
There are countless threads on forums of such vendors offering supply/fit, warranties etc etc and many many turn into a total nightmare with them supplying dodgy engines.

Of course every single one will not be like that, but there is huge risk involved....and that's just buying locally ! From Oz where you'd really have no backup or guarantees....not a chance would I take that risk.